Carl Andreas Lindstrøm

• Lindstrøm et al., Nat. Commun. 15, 6097 (2024), "Emittance preservation in a plasma-wakefield accelerator"
• Foster et al., New J. Phys. 25, 093037 (2023), “A hybrid, asymmetric, linear Higgs factory based on plasma-wakefield and radio-frequency acceleration”
• D’Arcy et al., Nature 603, 58 (2022), “Recovery time of a plasma-wakefield accelerator”
• Lindstrøm et al., Phys. Rev. Lett. 126, 014801 (2021), “Energy-spread preservation and high efficiency in a plasma-wakefield accelerator”
• Schröder et al., Nat. Commun. 11, 5984 (2020), “High-resolution sampling of beam-driven plasma wakefields”
• Deng et al., Nat. Phys. 15, 1156 (2019), “Generation and acceleration of electron bunches from a plasma photocathode”"
• Lindstrøm et al., Phys. Rev. Lett. 121, 194801 (2018), “Emittance preservation in an aberration-free active plasma lens”
• Lindstrøm et al., Phys. Rev. Lett. 120, 124802 (2018), “Measurement of transverse wakefields induced by a misaligned positron bunch in a hollow channel plasma accelerator”
• Gessner et al., Nat. Commun. 7, 11785 (2016), “Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator”

• Finnerud, Ole Gunnar; Adli, Erik; Ariniello, R; Corde, S; Dalichaouch, T N & Emma, C [Vis alle 21 forfattere av denne artikkelen] (2026). First results from the E302 efficiency–instability experiment at the FACET-II facility. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 3266(1). doi: 10.1088/1742-6596/3266/1/012001. Fulltekst i vitenarkiv Vis sammendrag

  Abstract The beam-breakup (BBU) instability in plasma accelerators is seeded by a transverse offset between the driver and a trailing bunch. The BBU instability induces oscillations in the trailing bunch, which are detrimental to its beam quality. When the instability is large, assuming little mitigation from ion motion and energy spread, the beam suffers emittance growth, and charge can be kicked transversely out of the plasma channel. The detrimental effect on beam quality is substantially worse at high efficiencies, which places constraints on the achievable power efficiency in applications such as linear colliders, where maintaining the beam quality is required. In this paper, we present the first experimental signatures of the BBU instability in data taken in the E302 experiment at the FACET-II facility at SLAC National Accelerator Laboratory. We use a specific beam-optical setup and a novel method to probe for transverse instabilities on diagnostic screens downstream of a magnetic dipole spectrometer. We complement the analysis with full 3D particle-in-cell (PIC) simulations of the plasma interaction using similar driver and trailing bunch parameters on a simulated FACET-II spectrometer.

• Sjobak, Kyrre Ness; Rød-Lindberg, E; Ellingsen, Abélia; Drobniak, Pierre; Rieker, Vilde Flognfeldt & Reaz, F [Vis alle 8 forfattere av denne artikkelen] (2026). SHARP: A compact focusing system for medical applications using a diverging plasma lens. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 3266(1), s. 012014–012014. doi: 10.1088/1742-6596/3266/1/012014. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Cancer therapy for deep-seated tumors requires precise irradiation of a small target deep within the patient while minimizing radiation exposure to surrounding tissues. This can be accomplished with a round beam sharply converging towards a single spot, requiring a large beam size in both planes at the exit of the focusing system. Achieving this over a short distance using only quadrupole lenses is challenging; but by using a linear active plasma lens (APL) in defocusing mode, the beam can be quickly and non-destructively enlarged before focusing using quadrupoles. The position of the irradiation spot can also be scanned in three dimensions by changing magnet settings. The SHARP project will develop and test this concept. Such a system can be used with very high energy electrons (hundreds of MeV), creating a Bragg-peak-like spot using novel accelerator technology. This could lead to more compact radiotherapy facilities, not requiring a bulky infrastructure typically associated with proton radiotherapy machines. If successful, SHARP will enable precision conformal radiotherapy, spatial fractionation, and potentially be useful for FLASH radiotherapy.

• Kalvik, Daniel; Lindstrøm, Carl A.; Peña, Felipe; Loisch, Gregor; Garland, James & Svensson, Jonas Björklund [Vis alle 16 forfattere av denne artikkelen] (2025). Ion-motion simulations of a plasma-wakefield experiment at FLASHForward. Proceedings of the International Particle Accelerator Conference. ISSN 2673-5490. s. 1442–1445. doi: 10.18429/JACOW-IPAC2025-TUPS013. Fulltekst i vitenarkiv Vis sammendrag

  In plasma-based acceleration, an ultra-relativistic particle bunch—or an intense laser beam—is used to expel electrons from its propagation path, forming a wake that is devoid of electrons. The ions, being significantly more massive, are often assumed to be stationary. However, both theory and simulations suggest that any sufficiently dense electron bunch can trigger ion motion, and its effect must be taken into account. We simulate beam-driven plasma wakefields to identify key features—such as longitudinally dependent emittance growth—that could be observed in an experiment using plasma and beam parameters from the FLASHForward facility at DESY.

• Adli, Erik; Lindstrøm, Carl A.; Kalvik, Daniel; Sjobak, Kyrre Ness; Finnerud, Ole Gunnar & Chen, Jian Bin Ben [Vis alle 7 forfattere av denne artikkelen] (2025). Transverse tolerances in the plasma-wakefield acceleration blow-out regime. Proceedings of the International Particle Accelerator Conference. ISSN 2673-5490. s. 1434–1437. doi: 10.18429/JACOW-IPAC2025-TUPS011. Fulltekst i vitenarkiv Vis sammendrag

  We report on recent progress in transverse instabilities and transverse tolerances for plasma-wakefield accelerators in the blow-out regime. In this regime, the transverse fields provide both strong focusing and strong deflection via transverse wakefields. The deflection effect of the wakefields on the main beam leads to limitations on the acceleration efficiency, if not mitigated. Based on comprehensive particle-in-cell simulations we summarize recent findings of the instability--efficiency relation for the blow-out regime. Ion motion and energy spread may mitigate the instability; with linac start-to-end simulations, using the recently developed ABEL framework, we demonstrate that the instability and emittance growth may be sufficiently mitigated for the colliding beams in the HALHF concept. Independent of wakefield effects, the strong focusing fields lead to very tight tolerances for the drive-beam jitter. We quantify these tolerances, using examples from HALHF start-to-end simulations. We show that the tolerances are greatly loosened by applying external magnetic fields to guide the drive-beam propagation in the plasma.

• Adli, Erik; D’Auria, Gerardo; Catalan Lasheras, Nuria; Cilento, Vera; Corsini, Roberto & Doebert, Steffen [Vis alle 474 forfattere av denne artikkelen] (2025). CLIC readiness report. The European Physical Journal Special Topics (EPJ - Special Topics (EPJ ST)). ISSN 1951-6355. 234(22), s. 6473–6652. doi: 10.1140/epjs/s11734-025-02016-w. Fulltekst i vitenarkiv
• Finnerud, Ole Gunnar; Lindstrøm, Carl Andreas; Chen, Jian Bin Ben & Adli, Erik (2025). The E302 instability-versus-efficiency experiment at FACET-II. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 3124(1). doi: 10.1088/1742-6596/3124/1/012005. Fulltekst i vitenarkiv Vis sammendrag

  We discuss plans for the E302 instability-efficiency experiment, starting in 2024 at the recently upgraded FACET-II facility at SLAC National Accelerator Laboratory. The beam-breakup instability will be the main area of study for the E302 experiment. With the imaging spectrometer at FACET-II, we introduce a novel technique for observing and quantifying the amplitude growth of the trailing bunch due to the transverse instability. Using the transverse position on the spectrometer screen and the transfer matrix of the magnetic lattice used for the spectrometer, we aim to extract a x′–E charge distribution that can be used to quantify the amplitude of the beam. By varying the trailing bunch’s charge and, hence, the beam loading of the accelerating field, we aim to adjust the wake-to-beam power transfer efficiency in the E302 experiment. We plan to quantify the amplitude for different configurations of the beam charge and, hence, investigate the relationship between the beam-breakup instability and efficiency. We use a combination of particle-in-cell (PIC) codes to simulate a beam-driven plasma wakefield accelerator from start-to-end with a FACET-II-like spectrometer and demonstrate the methodology that will be used for the instability studies at the E302 experiment.

• Lindstrøm, Carl Andreas; D'Arcy, R. & Foster, B. (2025). Status of and upgrade concepts for HALHF: the hybrid, asymmetric, linear Higgs factory. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 3124(1). doi: 10.1088/1742-6596/3124/1/012001. Fulltekst i vitenarkiv
• Chen, Jian Bin Ben; Lindstrøm, Carl Andreas; Finnerud, Ole Gunnar & Adli, Erik (2025). Modelling transverse instability in HALHF plasma stages. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 3124(1). doi: 10.1088/1742-6596/3124/1/012015. Fulltekst i vitenarkiv Vis sammendrag

  We present first results for a parameter study of the plasma linac of HALHF, a novel electron-positron collider concept combining plasma wakefield acceleration and mature RF acceleration to reach a centre of mass energy of 250 GeV. This study is a preliminary extension of the previous studies that indicated promising performance, by including transverse instability. Transverse instability was simulated using start-to-end simulations, where PIC simulations were combined with a simplified model to efficiently model transverse instability in the plasma-acceleration stages. No interstage optics were included. With a small initial transverse offset, the currently proposed parameter set will result in emittance growth and charge losses. If additional transverse misalignments are introduced between stages in the form of drive beam transverse jitter, the emittance growth is even more severe. Mitigation mechanisms to reduce the instability to an acceptable level are suggested.

• Zhang, Chaojie; Storey, Douglas; Knetsch, Alexander; O’Shea, Brendan D.; Ariniello, Robert & Cao, Jiawei [Vis alle 22 forfattere av denne artikkelen] (2025). Plasma-wakefield accelerator simultaneously boosts electron beam energy and brightness. Nature Communications. 16(1). doi: 10.1038/s41467-025-65742-8. Fulltekst i vitenarkiv Vis sammendrag

  High-energy particle colliders and X-ray free-electron lasers demand electron beams with qualities currently achieved only in kilometer-scale radio-frequency accelerators. Plasma accelerators promise a compact alternative but have faced challenges in delivering the needed beam quality at relevant energies. Here, we demonstrate that a plasma-wakefield accelerator operating in the nonlinear regime acts as a transformer to simultaneously boost the energy and brightness of an electron bunch injected from the plasma. Using a 10-GeV drive bunch and a three-stage meter-scale plasma source, we generated electron bunches exceeding 20 GeV with sub-percent energy spread, 2 mm·mrad normalized emittance, and multi-kA peak current. A significant number of drive-bunch electrons lost over 90% of their energy, a prerequisite for high energy-conversion efficiency. This demonstration of an energy transformer ratio exceeding two and a brightness enhancement over an order of magnitude opens a path towards cost-effective accelerators for future colliders and light sources.

• Finnerud, O. G.; Lindstrøm, Carl A. & Adli, Erik (2025). Parametric mapping of the efficiency–instability relation in plasma-wakefield accelerators. Physical Review Accelerators and Beams. ISSN 2469-9888. 28(7). doi: 10.1103/72qb-517d. Fulltekst i vitenarkiv Vis sammendrag

  High efficiency is essential for plasma-wakefield accelerators to be a cost-effective alternative in high-power applications, such as a linear collider. However, in a plasma-wakefield accelerator, the beam-breakup instability can be seeded by a transverse offset between the driver and trailing bunch. This instability, which rapidly increases the oscillation amplitude of the trailing bunch, grows with higher power-transfer efficiency from the driver to the trailing bunch [V. Lebedev et al., Phys. Rev. Accel. Beams 20, 121301 (2017)]. In this paper, we use particle-in-cell simulations to investigate the efficiency–instability relation that constrains the driver-to-trailing-bunch power-transfer efficiency in beam-driven plasma accelerators. We test the relation using a grid of simulations across all parameters that affect the beam-breakup instability, assuming a uniform accelerating field (optimal beam loading) and no ion motion. We find that the previously proposed efficiency–instability relation represents a lower limit on the strength of the instability for a given efficiency. For each normalized wake radius, only a certain accelerating field reaches this lowest value of the transverse instability; deviating from this point can increase the growth rate by several orders of magnitude. Finally, we highlight how the oscillation-amplitude growth of the trailing bunch can be reduced or damped with an initial uncorrelated energy spread and the presence of ion motion.

• Foster, Brian; Adli, Erik; Barklow, Timothy L.; Berggren, Mikael; Boogert, Stewart & Chen, Jian Bin Ben [Vis alle 24 forfattere av denne artikkelen] (2025). Proceedings of the Erice workshop: A new baseline for the hybrid, asymmetric, linear Higgs factory HALHF. Physics Open. 23. doi: 10.1016/j.physo.2025.100261. Fulltekst i vitenarkiv Vis sammendrag

  The HALHF collaboration has discussed a new baseline for the project, taking into account comments from the accelerator community on various aspects of the original design. In particular, these concerned the practicality of the dual-purpose linac to accelerate both colliding positron bunches and the drive beams required for the plasma linac. In addition, many other aspects of the project were also considered; the discussion and conclusions are documented in this paper. Finally, a new baseline is outlined that has been optimised and addresses several weaknesses in the original design, has higher luminosity, reduced centre-of-mass energy boost and additional features such as two interaction points and positron polarisation as well as electron polarisation. Although HALHF has become longer and more expensive, it remains significantly smaller and cheaper than other mature Higgs factory designs currently under discussion.

• Drobniak, Pierre Bony Henri; Adli, Erik; Anderson, Hektor Bergravf; Dyson, Anthony E; Mewes, S. M. & Sjobak, Kyrre Ness [Vis alle 8 forfattere av denne artikkelen] (2025). Development of a nonlinear plasma lens for achromatic beam transport. Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. ISSN 0168-9002. 1072. doi: 10.1016/j.nima.2025.170223. Fulltekst i vitenarkiv Vis sammendrag

  We introduce the new idea of a nonlinear active plasma lens, as part of a larger transport lattice for achromatic electron beam transport. The proposed implementation uses an external dipole magnet acting on a plasma and is motivated by 1D-hydrodynamic simulations. The manufactured design is presented, including its undergoing experimental characterisation on the CLEAR beam-line at CERN.

• Cao, Jiawei; Lindstrøm, Carl A.; Adli, Erik; Corde, Sébastien & Gessner, Spencer (2024). Positron acceleration in plasma wakefields. Physical Review Accelerators and Beams. ISSN 2469-9888. 27(3). doi: 10.1103/PhysRevAccelBeams.27.034801. Fulltekst i vitenarkiv Vis sammendrag

  Plasma acceleration has emerged as a promising technology for future particle accelerators, particularly linear colliders. Significant progress has been made in recent decades toward high-efficiency and high-quality acceleration of electrons in plasmas. However, this progress does not generalize to the acceleration of positrons, as plasmas are inherently charge asymmetric. Here, we present a comprehensive review of historical and current efforts to accelerate positrons using plasma wakefields. Proposed schemes that aim to increase energy efficiency and beam quality are summarized and quantitatively compared. A dimensionless metric that scales with the luminosity-per-beam power is introduced, indicating that positron-acceleration schemes are currently below the ultimate requirement for colliders. The primary issue is electron motion; the high mobility of plasma electrons compared to plasma ions, which leads to nonuniform accelerating and focusing fields that degrade the beam quality of the positron bunch, particularly for high efficiency acceleration. Finally, we discuss possible mitigation strategies and directions for future research.

• Peña, F.; Lindstrøm, Carl A.; Beinortaitė, J.; Svensson, J. Björklund; Boulton, L. & Diederichs, S. [Vis alle 16 forfattere av denne artikkelen] (2024). Energy depletion and re-acceleration of driver electrons in a plasma-wakefield accelerator. Physical Review Research (PRResearch). 6. doi: 10.1103/PhysRevResearch.6.043090. Fulltekst i vitenarkiv Vis sammendrag

  For plasma-wakefield accelerators to fulfill their potential for cost effectiveness, it is essential that their energy-transfer efficiency be maximized. A key aspect of this efficiency is the near-complete transfer of energy, or depletion, from the driver electrons to the plasma wake. Achieving full depletion is limited by the process of re-acceleration, which occurs when the driver electrons decelerate to nonrelativistic energies, slipping backward into the accelerating phase of the wakefield and being subsequently re-accelerated. Such re-acceleration is unambiguously observed here for the first time. At this re-acceleration limit, we measure a beam driver depositing (57 ± 3)% of its energy into a 195-mm-long plasma. This suggests that the energy-transfer efficiency of plasma accelerators could approach that of conventional accelerators.

• Lindstrøm, Carl Andreas; Beinortaite, Judita; Svensson, Jonas Björklund; Boulton, Lewis; Chappell, James & Diederichs, Severin [Vis alle 18 forfattere av denne artikkelen] (2024). Emittance preservation in a plasma-wakefield accelerator. Nature Communications. 15(1). doi: 10.1038/s41467-024-50320-1. Fulltekst i vitenarkiv Vis sammendrag

  Radio-frequency particle accelerators are engines of discovery, powering high- energy physics and photon science, but are also large and expensive due to their limited accelerating fields. Plasma-wakefield accelerators (PWFAs) pro- vide orders-of-magnitude stronger fields in the charge-density wave behind a particle bunch travelling in a plasma, promising particle accelerators of greatly reduced size and cost. However, PWFAs can easily degrade the beam quality of the bunches they accelerate. Emittance, which determines how tightly beams can be focused, is a critical beam quality in for instance colliders and free- electron lasers, but is particularly prone to degradation. We demonstrate, for the first time, emittance preservation in a high-gradient and high-efficiency PWFA while simultaneously preserving charge and energy spread. This establishes that PWFAs can accelerate without degradation—an essential step toward energy boosters in photon science and multistage facilities for com- pact high-energy particle colliders.

• Foster, Brian; D'Arcy, Richard & Lindstrøm, Carl A. (2023). A hybrid, asymmetric, linear Higgs factory based on plasma-wakefield and radio-frequency acceleration. New Journal of Physics. 25(9), s. 1–17. doi: 10.1088/1367-2630/acf395. Fulltekst i vitenarkiv Vis sammendrag

  The construction of an electron–positron collider 'Higgs factory' has been stalled for a decade, not because of feasibility but because of the cost of conventional radio-frequency (RF) acceleration. Plasma-wakefield acceleration promises to alleviate this problem via significant cost reduction based on its orders-of-magnitude higher accelerating gradients. However, plasma-based acceleration of positrons is much more difficult than for electrons. We propose a collider scheme that avoids positron acceleration in plasma, using a mixture of beam-driven plasma-wakefield acceleration to high energy for the electrons and conventional RF acceleration to low energy for the positrons. We emphasise the benefits of asymmetric energies, asymmetric bunch charges and asymmetric transverse emittances. The implications for luminosity and experimentation at such an asymmetric facility are explored and found to be comparable to conventional facilities; the cost is found to be much lower. Some of the areas in which R&D is necessary to make HALHF a reality are highlighted, including estimates for the improvement required in key technologies. These range from a factor of 10 to a factor of 1000.

• Barklow, Tim; Gessner, Spencer; Hogan, Mark; Ng, Cho-Kuen; Peskin, Michael & Raubenheimer, Tor [Vis alle 30 forfattere av denne artikkelen] (2023). Beam delivery and beamstrahlung considerations for ultra-high energy linear colliders. Journal of Instrumentation (JINST). 18(9). doi: 10.1088/1748-0221/18/09/P09022. Fulltekst i vitenarkiv
• White, G.; Gessner, S.; Adli, Erik; Cao, Jiawei; Sjobak, Kyrre Ness & Barber, S. [Vis alle 15 forfattere av denne artikkelen] (2022). Beam delivery and final focus systems for multi-TeV advanced linear colliders. Journal of Instrumentation (JINST). 17(5). doi: 10.1088/1748-0221/17/05/P05042. Fulltekst i vitenarkiv Vis sammendrag

  The Beam Delivery System (BDS) is a critical component of a high-energy linear collider. It transports the beam from the accelerator and brings it to a focus at the Interaction Point. The BDS system includes diagnostic sections for measuring the beam energy, emittance, and polarization, as well as collimators for machine protection. The length of the BDS increases with collision energy. Higher collision energies also require higher luminosities, and this is a significant constraint on the design for energy-frontier machines. Here, we review BDS designs based on traditional quadrupole magnets and examine the challenges involved in extending these to the Multi-TeV regime consistent with requirements for advanced accelerator concepts.

• Sjobak, Kyrre Ness; Adli, Erik; Corsini, Roberto; Farabolini, Wilfrid; Boyle, Gregory & Lindstrøm, Carl A. [Vis alle 11 forfattere av denne artikkelen] (2021). Strong focusing gradient in a linear active plasma lens. Physical Review Accelerators and Beams. ISSN 2469-9888. 24(12). doi: 10.1103/PhysRevAccelBeams.24.121306. Fulltekst i vitenarkiv Vis sammendrag

  Active plasma lenses are compact devices developed as a promising beam-focusing alternative for charged particle beams, capable of short focal lengths for high-energy beams. We have previously shown that linear magnetic fields with gradients of around 0.3 kT/m can be achieved in argon-filled plasma lenses that preserve beam emittance [C.A. Lindstrøm et al., Phys. Rev. Lett. 121, 194801 (2018)]. Here we show that with argon in a 500  μm diameter capillary, the fields are still linear with a focusing gradient of 3.6 kT/m, which is an order of magnitude higher than the gradients of quadrupole magnets. The current pulses that generate the magnetic field are provided by compact Marx banks, and are highly repeatable. The demonstrated operation with simultaneously high-gradient, linear fields and good repeatability establish active plasma lenses as an ideal device for pulsed particle beam applications requiring very high focusing gradients that are uniform throughout the lens aperture.

• Vafaei-Najafabadi, N.; Amorim, L. D.; Adli, Erik; An, W; Clarke, C. I. & Clayton, C. E. [Vis alle 24 forfattere av denne artikkelen] (2019). Producing multi-coloured bunches through beam-induced ionization injection in plasma wakefield accelerator. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. ISSN 1364-503X. 377(2151), s. 1–13. doi: 10.1098/rsta.2018.0184. Fulltekst i vitenarkiv
• Lindstrøm, Carl A.; Adli, Erik; Boyle, Gregory; Corsini, Roberto; Dyson, Anthony E & Farabolini, Wilfrid [Vis alle 12 forfattere av denne artikkelen] (2018). Emittance Preservation in an Aberration-Free Active Plasma Lens. Physical Review Letters. ISSN 0031-9007. 121(19), s. 194801-1–194801-6. doi: 10.1103/PhysRevLett.121.194801. Fulltekst i vitenarkiv Vis sammendrag

  Active plasma lensing is a compact technology for strong focusing of charged particle beams, which has gained considerable interest for use in novel accelerator schemes. While providing kT=m focusing gradients, active plasma lenses can have aberrations caused by a radially nonuniform plasma temperature profile, leading to degradation of the beam quality. We present the first direct measurement of this aberration, consistent with theory, and show that it can be fully suppressed by changing from a light gas species (helium) to a heavier gas species (argon). Based on this result, we demonstrate emittance preservation for an electron beam focused by an argon-filled active plasma lens.

• Lindstrøm, Carl A.; Sjøbæk, Kyrre Ness; Adli, Erik; Röckemann, J.-H.; Schaper, L. & Osterhoff, J. [Vis alle 11 forfattere av denne artikkelen] (2018). Overview of the CLEAR plasma lens experiment. Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. ISSN 0168-9002. 909, s. 379–382. doi: 10.1016/j.nima.2018.01.063. Fulltekst i vitenarkiv Vis sammendrag

  Discharge capillary-based active plasma lenses are a promising new technology for strongly focusing charged particle beams, especially when combined with novel high gradient acceleration methods. Still, many questions remain concerning such lenses, including their transverse field uniformity, limitations due to plasma wakefields and whether they can be combined in multi-lens lattices in a way to cancel chromaticity. These questions will be addressed in a new plasma lens experiment at the CLEAR User Facility at CERN. All the subsystems have been constructed, tested and integrated into the CLEAR beam line, and are ready for experiments starting late 2017.

• Lindstrøm, Carl A.; Adli, Erik; Allen, James M.; An, Weiming; Beekman, C. & Clarke, Christine I. [Vis alle 21 forfattere av denne artikkelen] (2018). Measurement of Transverse Wakefields Induced by a Misaligned Positron Bunch in a Hollow Channel Plasma Accelerator. Physical Review Letters. ISSN 0031-9007. 120:124802(12), s. 1–5. doi: 10.1103/PhysRevLett.120.124802. Fulltekst i vitenarkiv Vis sammendrag

  Hollow channel plasma wakefield acceleration is a proposed method to provide high acceleration gradients for electrons and positrons alike: a key to future lepton colliders. However, beams which are misaligned from the channel axis induce strong transverse wakefields, deflecting beams and reducing the collider luminosity. This undesirable consequence sets a tight constraint on the alignment accuracy of the beam propagating through the channel. Direct measurements of beam misalignment-induced transverse wakefields are therefore essential for designing mitigation strategies. We present the first quantitative measurements of transverse wakefields in a hollow plasma channel, induced by an off-axis 20 GeV positron bunch, and measured with another 20 GeV lower charge trailing positron probe bunch. The measurements are largely consistent with theory.

• Doche, A.; Beekman, C.; Corde, S.; Allen, J. M.; Clarke, C. I. & Frederico, J. [Vis alle 21 forfattere av denne artikkelen] (2017). Acceleration of a trailing positron bunch in a plasma wakefield accelerator. Scientific Reports. 7(1). doi: 10.1038/s41598-017-14524-4. Fulltekst i vitenarkiv Vis sammendrag

  High gradients of energy gain and high energy efficiency are necessary parameters for compact, cost-efficient and high-energy particle colliders. Plasma Wakefield Accelerators (PWFA) offer both, making them attractive candidates for next-generation colliders. In these devices, a charge-density plasma wave is excited by an ultra-relativistic bunch of charged particles (the drive bunch). The energy in the wave can be extracted by a second bunch (the trailing bunch), as this bunch propagates in the wake of the drive bunch. While a trailing electron bunch was accelerated in a plasma with more than a gigaelectronvolt of energy gain, accelerating a trailing positron bunch in a plasma is much more challenging as the plasma response can be asymmetric for positrons and electrons. We report the demonstration of the energy gain by a distinct trailing positron bunch in a plasma wakefield accelerator, spanning nonlinear to quasi-linear regimes, and unveil the beam loading process underlying the accelerator energy efficiency. A positron bunch is used to drive the plasma wake in the experiment, though the quasi-linear wake structure could as easily be formed by an electron bunch or a laser driver. The results thus mark the first acceleration of a distinct positron bunch in plasma-based particle accelerators.

• Gamba, D.; Corsini, Roberto; Curt, S.; Doebert, Steffen; Farabolini, W. & McMonagle, G. [Vis alle 13 forfattere av denne artikkelen] (2017). The CLEAR user facility at CERN. Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. ISSN 0168-9002. 909, s. 480–483. doi: 10.1016/j.nima.2017.11.080. Fulltekst i vitenarkiv Vis sammendrag

  The conversion of the CALIFES beamline of CTF3 into the ‘‘CERN Linear Electron Accelerator for Research’’ (CLEAR) facility was approved in December 2016. The primary focus for CLEAR is general accelerator R&D and component studies for existing and possible future accelerator applications. This includes studies for high gradient acceleration methods, e.g. for CLIC and plasma technology, and prototyping and validation of accelerator components, e.g. for the HL-LHC upgrade. The facility also provides irradiation test capabilities for characterisation of electronic components and for medical applications. A description of the facility with details on the achievable beam parameters, and the status and plans are presented.

• Hidding, B.; Manahan, G. G.; Heinemann, T.; Scherkl, P.; Habib, F. & Ullmann, D. [Vis alle 28 forfattere av denne artikkelen] (2017). FIRST MEASUREMENTS OF TROJAN HORSE INJECTION IN A PLASMA WAKEFIELD ACCELERATOR, Proceedings of the 8th International Particle Accelerator Conference. JACoW. ISSN 9783954501823. s. 1252–1257. Fulltekst i vitenarkiv Vis sammendrag

  Plasma accelerators support accelerating fields of 10-100’s of GV/m over meter-scale distances and routinely produce femtosecond-scale, multi-kA electron bunches. The so called Trojan Horse underdense photocathode plasma wakefield acceleration scheme combines state of-the-art accelerator technology with laser and plasma methods and paves the way to improve beam quality as regards emittance and energy spread by many orders of magnitude. Electron beam brightness levels exceeding 10^20 A m^-2 rad^-2 may be reached, and the tunability allows for multi-GeV energies, designer bunches and energy spreads <0.05% in a single plasma accelerator stage. The talk will present results of the international E210 multiyear experimental program at SLAC FACET, which culminated in successful first demonstration of the Trojan Horse method during FACET’s final experimental run in 2016. Enabling implications for applications, including high performance plasma-based 5th generation light sources such as hard x-ray FEL’s, for which preliminary start-to-end simulations are presented, and for high energy physics are discussed.

• Lindstrøm, Carl Andreas; Adli, Erik; Allen, James; Delahaye, Jean-Pierre; Hogan, Mark J. & Joshi, Chan [Vis alle 9 forfattere av denne artikkelen] (2016). Staging Optics Considerations for a Plasma Wakefield Acceleration Linear Collider. Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. ISSN 0168-9002. 829, s. 224–228. doi: 10.1016/j.nima.2015.12.065. Fulltekst i vitenarkiv Vis sammendrag

  Plasma wakefield acceleration offers acceleration gradients of several GeV/m, ideal for a next-generation linear collider. The beam optics requirements between plasma cells include injection and extraction of drive beams, matching the main beam beta functions into the next cell, canceling dispersion as well as constraining bunch lengthening and chromaticity. To maintain a high effective acceleration gradient, this must be accomplished in the shortest distance possible. A working example is presented, using novel methods to correct chromaticity, as well as scaling laws for a high energy regime.

• Adli, Erik; Lindstrøm, Carl Andreas; Allen, J.; Clarke, C. I.; Frederico, J. & Gessner, S.J. [Vis alle 19 forfattere av denne artikkelen] (2016). Long-range attraction of an ultrarelativistic electron beam by a column of neutral plasma. New Journal of Physics. 18(103013). doi: 10.1088/1367-2630/18/10/103013. Fulltekst i vitenarkiv Vis sammendrag

  We report on the experimental observation of the attraction of a beam of ultrarelativistic electrons towards a column of neutral plasma. In experiments performed at the FACET test facility at SLAC we observe that an electron beam moving parallel to a neutral plasma column, at an initial distance of many plasma column radii, is attracted into the column. Once the beam enters the plasma it drives a plasma wake similar to that of an electron beam entering the plasma column head-on. A simple analytical model is developed in order to capture the essential physics of the attractive force. The attraction is further studied by 3D particle-in-cell numerical simulations. The results are an important step towards better understanding of particle beam–plasma interactions in general and plasma wakefield accelerator technology in particular.

• Adli, Erik; Olsen, Veronica Kristine Berglyd; Lindstrøm, Carl Andreas; Muggli, Patric; Reimann, O. & Vieira, Jorge [Vis alle 20 forfattere av denne artikkelen] (2016). Progress of plasma wakefield self-modulation experiments at FACET. Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. ISSN 0168-9002. 829, s. 334–338. doi: 10.1016/j.nima.2016.02.075. Fulltekst i vitenarkiv Vis sammendrag

  Simulations and theory predict that long electron and positron beams may under favorable conditions self-modulate in plasmas. We report on the progress of experiments studying the self-modulation instability in plasma wakefield experiments at FACET. The experimental results obtained so far, while not being fully conclusive, appear to be consistent with the presence of the self-modulation instability.

• Gessner, Spencer; Adli, Erik; Allen, James; An, Weiming; Clarke, Christine & Clayton, Christopher E. [Vis alle 24 forfattere av denne artikkelen] (2016). Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator. Nature Communications. 7:11785. doi: 10.1038/ncomms11785. Fulltekst i vitenarkiv Vis sammendrag

  Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV/m is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.

• Adli, Erik; Lindstrøm, Carl Andreas; Allen, James; Clarke, Christine; Frederico, Joel & Gessner, Spencer [Vis alle 19 forfattere av denne artikkelen] (2016). Transverse oscillations in plasma wakefield experiments at FACET. Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment. ISSN 0168-9002. 829, s. 94–98. doi: 10.1016/j.nima.2016.02.054. Fulltekst i vitenarkiv Vis sammendrag

  We study transverse effects in a plasma wakefield accelerator. Experimental data from FACET with asymmetry in the beam-plasma system is presented. Energy dependent centroid oscillations are observed on the accelerated part of the charge. The experimental results are compared to PIC simulations and theoretical estimates.

• Lindstrøm, Carl Andreas & Adli, Erik (2016). Design of general apochromatic drift-quadrupole beam lines. Physical Review Special Topics. Accelerators and Beams. 19:071002(7). doi: 10.1103/PhysRevAccelBeams.19.071002. Fulltekst i vitenarkiv Vis sammendrag

  Chromatic errors are normally corrected using sextupoles in regions of large dispersion. In low emittance linear accelerators, use of sextupoles can be challenging. Apochromatic focusing is a lesser-known alternative approach, whereby chromatic errors of Twiss parameters are corrected without the use of sextupoles, and has consequently been subject to renewed interest in advanced linear accelerator research. Proof of principle designs were first established by Montague and Ruggiero and developed more recently by Balandin et al. We describe a general method for designing drift-quadrupole beam lines of arbitrary order in apochromatic correction, including analytic expressions for emittance growth and other merit functions. Worked examples are shown for plasma wakefield accelerator staging optics and for a simple final focus system.

• Gessner, Spencer; Allen, James; Clarke, Christine; Delahaye, Jean-Pierre; Frederico, Joel & Green, Selina [Vis alle 25 forfattere av denne artikkelen] (2016). Demonstration of the hollow channel plasma wakefield accelerator. I Petit-Jean-Genaz, Christine; Kim, Dong Eon; Kim, Kyung Sook; Ko, In Soo; Kim, Kyung Ryul & Schaa, Volker RW (Red.), Proceedings of the 7th International Particle Accelerator Conference. JACoW. ISSN 9783954501472. s. 3202–3206. Fulltekst i vitenarkiv Vis sammendrag

  Over the past decade, there has been enormous progress in the field of beam and laser-driven plasma acceleration of electron beams. However, in order for plasma wakefield acceleration to be useful for a high-energy e+e−collider, we need a technique for accelerating positrons in plasma as well. This is a unique challenge, because the plasma responds differently to electron and positron beams, with plasma electrons being pulled through the positron beam and creating a non-linear focusing force that is disruptive to the beam. Here, we demonstrate a technique called hollow channel acceleration that symmetrizes the wakefield response to beams of either charge. Using a transversely shaped laser pulse, we create an annular plasma with a fixed radius of 200 μIm. We observe the acceleration of a positron bunch with energies up to 33.4 MeV in a 25 cm long channel, indicating an effective gradient greater than 100 MeV/m. This is the first demonstration of a technique that way be used for staged acceleration of positron beams in plasma.

• Lindstrøm, Carl Andreas; Adli, Erik; Pfingstner, Juergen; Marin, E. & Schulte, D (2016). Transverse tolerances of a multi-stage plasma wakefield accelerator. I Petit-Jean-Genaz, Christine; Kim, Dong Eon; Kim, Kyung Sook; Ko, In Soo; Kim, Kyung Ryul & Schaa, Volker RW (Red.), Proceedings of the 7th International Particle Accelerator Conference. JACoW. ISSN 9783954501472. s. 2561–2564. Fulltekst i vitenarkiv Vis sammendrag

  Plasma wakefield acceleration (PWFA) provides GeV/m-scale accelerating fields, ideal for applications such as a future linear collider. However, strong focusing fields imply that a transversely offset beam with an energy spread will experience emittance growth from the energy depen- dent betatron oscillation. We develop an analytic model for estimating tolerances from this effect, as well as an effective simplified simulation tool in Elegant. Estimations for a proposed 1 TeV PWFA linear collider scheme indicate tight tolerances of order 40 nm and 1 μrad in position and angle respectively.

• Pfingstner, Juergen; Adli, Erik; Lindstrøm, Carl Andreas; Marin, E. & Schulte, D (2016). Considerations for a drive beam scheme for a plasma wakefield linear collider. I Petit-Jean-Genaz, Christine; Kim, Dong Eon; Kim, Kyung Sook; Ko, In Soo; Kim, Kyung Ryul & Schaa, Volker RW (Red.), Proceedings of the 7th International Particle Accelerator Conference. JACoW. ISSN 9783954501472. s. 2565–2568. Fulltekst i vitenarkiv Vis sammendrag

  The potential for high average gradients makes plasma wakefield acceleration (PWFA) an attracting option for future linear colliders. For a beam-driven PWFA collider a sequence of cells has to be supplied with synchronised drive beam bunches. This paper is concerned with the generation, transport and distribution of these drive beam bunches in a so-called drive beam complex for a 3 TeV collider. Based on earlier concepts, several modifications are suggested. The new design includes a superconducting linac and an optimised bunch delay system with a tree structure. To verify the feasibility for the overall complex, a lattice design and tracking studies for the critical bending arc subsystem are presented. Also the feasibility of a compact bunch separation system is shown. The result of these efforts is a drive beam complex that is optimised for construction cost and power efficiency that favours unified lattice solutions.

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• Ellingsen, Abélia; Adli, Erik; Drobniak, Pierre; Lindstrøm, Carl A.; Rød-Lindbergh, Elisabeth & Rieker, Vilde Flognfeldt [Vis alle 14 forfattere av denne artikkelen] (2026). SHARP: A Compact Focusing System for Emerging Particle Therapies using an Active Plasma Lens. doi: https:/indico.desy.de/event/51069/contributions/205605/. Fulltekst i vitenarkiv Vis sammendrag

  Background: Improved control of the beam envelope in particle radiotherapy could enhance the precision of dose delivery. A novel approach is to incorporate an active plasma lens (APL) into the beamline. This compact device is used for strong and radially symmetric defocusing, giving rapid and controlled beam expansion. Such an expanded beam is of interest in itself, as it is generated by beam optics rather than through scattering, enabling large high intensity fields that may be relevant for FLASH applications. Beam expansion can also be followed by downstream refocusing to produce a sharp waist at the target. This may reduce entrance dose to healthy tissue while enhancing dose deposition at depth. Such beam geometries from a compact system could benefit precision conformal radiotherapy and spatial fractionation. The SHARP project is in the process of demonstrating these ideas experimentally with 200 MeV very high-energy electrons (VHEE), supported by simulations of beam optics and dose distributions. Materials and Methods: Experiments are being conducted at the CLEAR facility at CERN. The system combines a defocusing APL with quadrupole magnets for final focusing onto the target. Beam enlargement, without focusing, is evaluated on a downstream profile monitoring screen. The refocused beam is subsequently characterized with screens downstream of the quadrupoles. Radiation transport simulations in Geant4 are used to model dose deposition at the target and outside the focal region. Simulations with ImpactX are used for designing beam optics and assessing the influence of e.g. energy spread. Results: Beam enlargement from the APL is experimentally observed to be linear and symmetric in both transverse planes. Simulations show that quadrupoles can modify these beams into large, quasi-parallel fields for broad irradiation of higher intensity than passive scattering, which could be useful to investigate further for certain FLASH applications. For small deep targets, simulations show that increasing the APL current coupled with refocusing quadrupoles reduces focal beam size while increasing divergence, producing a sharp Bragg-like peak. Larger opening angles upstream and downstream of the target have also been confirmed experimentally. Conclusions: SHARP investigates a compact hybrid APL-quadrupole system to achieve precise focal spots and controlled dose distributions. The technique could serve as a versatile research platform for SFRT and FLASH applications. The project’s first experimental results represent a promising step towards improved dose delivery by demonstrating both controlled beam enlargement and refocusing. Ongoing work to refine the concept includes simulations and experiments of scattering in water phantoms, nonlinear APL defocusing for generating enlarged flat fields, spot scanning, and extension of the concept to protons.

• Drobniak, Pierre; Adli, Erik; Anderson, H. B.; Sjobak, Kyrre Ness; Lindstrøm, Carl A. & Dyson, A. [Vis alle 8 forfattere av denne artikkelen] (2025). Preliminary results from the CLEAR nonlinear plasma lens experiment. doi: 10.18429/JACOW-IPAC2025-MOPS027. Fulltekst i vitenarkiv Vis sammendrag

  Plasma lensing provides compact focusing of electron beams, since they offer strong focusing fields (kT/m) in both planes simultaneously. This becomes particularly important for highly diverging beams with a large energy spread such as those typically originating from plasma accelerators. The lens presented here is a nonlinear active plasma lens, with a controlled focusing-strength variation purposely introduced in one transverse direction. This lens is a key element of a larger transport lattice, core of the ERC project SPARTA, which aims to provide a solution for achromatic transport between plasma-accelerator stages. We report on preliminary experimental results from the CLEAR facility at CERN, which aims to probe the magnetic field structure of the lens using an electron beam, in search of the desired nonlinearity, together with 2D plasma simulation results.

• Lindstrøm, Carl A.; Adli, Erik; Anderson, Hektor B.; Drobniak, Pierre; Kalvik, Daniel & Peña, Felipe [Vis alle 7 forfattere av denne artikkelen] (2025). The SPARTA project: toward a demonstrator facility for multistage plasma acceleration. doi: 10.18429/JACOW-IPAC2025-TUPS120. Fulltekst i vitenarkiv Vis sammendrag

  Plasma acceleration is a rapidly maturing technology, but is not yet ready for large-scale applications such as linear colliders. The SPARTA project aims to develop a near-term, medium-scale plasma-accelerator facility to enable new experiments in strong-field quantum electrodynamics (SFQED)—an application that requires solving two of the most important remaining challenges in plasma acceleration: reaching high energy by using multiple accelerating stages; and achieving high beam stability. We report on progress toward the three main objectives: demonstrating a nonlinear plasma lens for achromatic beam transport between stages; developing self-stabilization and instability suppression mechanisms; and developing a conceptual design for a multistage SFQED facility.

• Chen, Jian Bin Ben; Adli, Erik; Drobniak, Pierre; Finnerud, Ole Gunnar; Hørlyk, Eir Eline & Kalvik, Daniel [Vis alle 9 forfattere av denne artikkelen] (2025). ABEL: The adaptable beginning-to-end linac simulation framework. doi: 10.18429/JACOW-IPAC2025-TUPS012. Fulltekst i vitenarkiv Vis sammendrag

  We introduce ABEL, the Adaptable Beginning-to-End Linac simulation framework developed for agile design studies of plasma-based accelerators and colliders. ABEL’s modular architecture allows users to simulate particle acceleration across various beamline components. The framework supports specialised codes such as HiPACE++, Wake-T, ELEGANT, GUINEA-PIG and CLICopti, which facilitate precise modelling of complex machine components. Key features include simplified models for addressing transverse instabilities, radiation reactions, and ion motion, alongside comprehensive diagnostics and optimisation capabilities. Our simulation studies focus on the HALHF plasma linac, examining tolerances for drive beam jitter, including effects of self-correction mechanisms. Simulation results demonstrate ABEL's ability to model emittance growth under transverse instability and ion motion, highlighting the framework’s adaptability in balancing simulation fidelity with computational efficiency. The findings point towards ABEL’s potential for advancing compact accelerator designs and contribute to the broader goals of enhancing control and precision in plasma-based acceleration.

• Peña, Felipe; Adli, Erik; Drobniak, Pierre; Kalvik, Daniel; Sjobak, Kyrre Ness & Lindstrøm, Carl A. (2025). Development of an achromatic spectrometer for a laser-wakefield-accelerator experiment. doi: 10.18429/JACOW-IPAC2025-TUPM096. Fulltekst i vitenarkiv Vis sammendrag

  The large gradients of plasma-wakefield accelerators promise to shorten accelerators and reduce their financial and environmental costs. For such accelerators, a key challenge is the transport of beams with high divergence and energy spread. Achromatic optics is a potential solution that would allow staging of plasma accelerators without beam-quality degradation. For this, a nonlinear plasma lens is being developped within the SPARTA project. As a first application of this lens, we aim to implement an achromatic spectrometer for electron bunches produced by a laser-wakefield accelerator. We report on progress in designing such an experiment.

• Lindstrøm, Carl A.; Adli, Erik; Chen, Jian Bin Ben; Drobniak, Pierre; Hørlyk, Eir Eline & Kalvik, Daniel [Vis alle 28 forfattere av denne artikkelen] (2025). Updated baseline design for HALHF: the hybrid, asymmetric, linear Higgs factory. doi: 10.18429/JACOW-IPAC2025-MOCD1. Fulltekst i vitenarkiv Vis sammendrag

  Particle physicists aim to construct a electron–positron Higgs factory as the next major particle collider. However, the high associated costs motivate the development of more affordable collider designs. Plasma-wakefield acceleration is a promising technology to this end. HALHF is a proposal for a Higgs factory that utilizes beam-driven plasma-wakefield acceleration to accelerate electrons to high energy with high gradient, while using radio-frequency acceleration to accelerate positrons to a lower energy. This asymmetry sidesteps a major difficulty in plasma acceleration: that of accelerating positrons with high efficiency and quality. Since publication, several challenges were identified in the original baseline design. We summarize the updated baseline design, which addresses these challenges, and describe the parameter- and cost-optimization process used to arrive at this design.

• Sjobak, Kyrre Ness; Adli, Erik; Bergamaschi, Michele; Burger, Stephane; Corsini, Roberto & Curcio, Alessandro [Vis alle 30 forfattere av denne artikkelen] (2019). Status of the CLEAR electron beam user facility at CERN. Fulltekst i vitenarkiv Vis sammendrag

  The CERN Linear Electron Accelerator for Research (CLEAR) has now finished its second year of operation, providing a testbed for new accelerator technologies and a versatile radiation source. Hosting a varied experimental program, this beamline provides a flexible test facility for users both internal and external to CERN, as well as being an excellent accelerator physics training ground. The energy can be varied between 60 and 220 MeV, bunch length between 1 and 4 ps, bunch charge in the range 10 pC to 2 nC, and number of bunches in the range 1 to 200, at a repetition rate of 0.8 to 10 Hz. The status of the facility with an overview of the recent experimental results is presented.

• Corsini, Roberto; Gamba, Davide; Farabolini, Wilfrid; Curcio, Alessandro; Doebert, Steffen & Alía, Rubén García [Vis alle 16 forfattere av denne artikkelen] (2018). FIRST EXPERIMENTS AT THE CLEAR USER FACILITY. Fulltekst i vitenarkiv
• Lindstrøm, Carl Andreas (2016). Experimental Measurements of the Hollow Channel PWFA Transverse Instability. Fulltekst i vitenarkiv
• Lindstrøm, Carl Andreas (2016). Emittance preserving staging optics for PWFA and LWFA. Fulltekst i vitenarkiv
• Adli, Erik & Lindstrøm, Carl Andreas (2016). Long-range attraction of an ultrarelativistic electron beam by a column of neutral plasma. Fulltekst i vitenarkiv
• Lindstrøm, Carl Andreas (2015). Ideas for a sextupole-free final focus system. Fulltekst i vitenarkiv
• Muggli, Patric; Reimann, O.; Amorim, L. D.; Lopes, N. C.; Silva, L. O. & Vieira, J. M. [Vis alle 22 forfattere av denne artikkelen] (2015). Measuring the Self-modulation Instability of Electron and Positron Bunches in Plasmas, Proceedings of the 6th International Particle Accelerator Conference. Jefferson Lab, Newport News. ISSN 9783954501687. s. 2506–2508. Fulltekst i vitenarkiv Vis sammendrag

  We briefly describe some of the features of the E209 experiment at SLAC-FACET. The experiment aims at studying the physics of the self-modulation instability of long electron and positron bunches in dense plasmas. Encouraging initial results were obtained so far. Further experiments will take place soon.

• Lindstrøm, Carl Andreas (2015). Interstage optics design for a plasma wakefield linear collider. Fulltekst i vitenarkiv Vis sammendrag

  Plasma wakefield acceleration offers acceleration gradients of several GeV/m as well as high power efficiency, ideal for a next-generation linear collider. The beam optics requirements between each plasma stage include injection and extraction of drive beams, controlling and matching the main beam beta functions to the plasma, cancelling dispersion as well as constraining bunch lengthening and chromaticity. To maintain a high effective acceleration gradient, this must be accomplished in the shortest distance possible. We present scaling laws for a working design, including a discussion of novel methods to address chromaticity correction.

• Lindstrøm, Carl Andreas (2015). Framework for global chromaticity correction using linear optics, with applications to plasma wakefield staging optics. Fulltekst i vitenarkiv
• Lindstrøm, Carl Andreas; Adli, Erik & Olsen, Veronica Kristine Berglyd (2015). Nå tar også positronene bølgen. [Internet]. Fysisk Institutt: Forskning. Fulltekst i vitenarkiv
• Lindstrøm, Carl Andreas (2015). Interstage Optics Design for a PWFA Linear Collider. Fulltekst i vitenarkiv
• Finnerud, Ole Gunnar; Adli, Erik & Lindstrøm, Carl A. (2026). Beam-breakup instability and efficiency in plasma accelerators. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Particle colliders have been important tools in particle physics since the early 20th century. However, the growing demand for larger and higher-energy particle accelerators is driving up their cost. Plasma-based colliders have emerged as a candidate for reducing their size and cost thanks to their higher accelerating gradients. A major obstacle for this emerging technology is the efficiency—instability relation, which states that at higher efficiencies, the beam becomes more unstable, eventually breaking apart. This thesis tackles this issue through numerical simulations and experimental studies. The efficiency—instability relation is shown to be a lower bound on the strength of the instability, which varies by a large amount depending on the accelerator parameters, indicating the importance of choosing an optimal operating point. The effect of mitigation strategies is shown to be significant while also dependent on the parameters chosen. An experiment is carried out to probe the instability using novel measurement techniques. The results show indications of the instability, its correlation with efficiency, and mitigating effects. The efficiency—instability relation is complicated to measure and not fully understood in theory, but studies like the ones outlined in this thesis are important milestones towards a better understanding of it.

• Lindstrøm, Carl A. (2019). Emittance growth and preservation in a plasmabased linear collider. Universitetet i Oslo. Fulltekst i vitenarkiv

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