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33 results on '"Karsch, S"'

1. Pareto Optimization of a Laser Wakefield Accelerator

Author

Irshad, F., Eberle, C., Foerster, F. M., Grafenstein, K. v., Haberstroh, F., Travac, E., Weisse, N., Karsch, S., and Döpp, A.

Subjects
Physics - Accelerator Physics, Computer Science - Machine Learning, Physics - Plasma Physics
Abstract

Optimization of accelerator performance parameters is limited by numerous trade-offs and finding the appropriate balance between optimization goals for an unknown system is challenging to achieve. Here we show that multi-objective Bayesian optimization can map the solution space of a laser wakefield accelerator in a very sample-efficient way. Using a Gaussian mixture model, we isolate contributions related to an electron bunch at a certain energy and we observe that there exists a wide range of Pareto-optimal solutions that trade beam energy versus charge at similar laser-to-beam efficiency. However, many applications such as light sources require particle beams at a certain target energy. Once such a constraint is introduced we observe a direct trade-off between energy spread and accelerator efficiency. We furthermore demonstrate how specific solutions can be exploited using \emph{a posteriori} scalarization of the objectives, thereby efficiently splitting the exploration and exploitation phases.

Published
2023

2. Measuring spatio-temporal couplings using modal spatio-spectral wavefront retrieval

Author

Weiße, N., Esslinger, J., Howard, S., Foerster, F. M., Haberstroh, F., Doyle, L., Norreys, P., Schreiber, J., Karsch, S., and Doepp, A.

Subjects
Physics - Optics
Abstract

Knowledge of spatio-temporal couplings such as pulse-front tilt or curvature is important to determine the focused intensity of high-power lasers. Common techniques to diagnose these couplings are either qualitative or require hundreds of measurements. Here we present both a new algorithm for retrieving spatio-temporal couplings, as well as novel experimental implementations. Our method is based on the expression of the spatio-spectral phase in terms of a Zernike-Taylor basis, allowing us to directly quantify the coefficients for common spatio-temporal couplings. We take advantage of this method to perform quantitative measurements using a simple experimental setup, consisting of different bandpass filters in front of a Shack-Hartmann wavefront sensor. This fast acquisition of laser couplings using narrowband filters, abbreviated FALCON, is easy and cheap to implement in existing facilities. To this end, we present a measurement of spatio-temporal couplings at the ATLAS-3000 petawatt laser using our technique.

Published
2023

3. Stable and high quality electron beams from staged laser and plasma wakefield accelerators

Author

Foerster, F. M., Döpp, A., Haberstroh, F., Grafenstein, K. v., Campbell, D., Chang, Y. -Y., Corde, S., Cabadağ, J. P. Couperus, Debus, A., Gilljohann, M. F., Habib, A. F., Heinemann, T., Hidding, B., Irman, A., Irshad, F., Knetsch, A., Kononenko, O., de la Ossa, A. Martinez, Nutter, A., Pausch, R., Schilling, G., Schletter, A., Schöbel, S., Schramm, U., Travac, E., Ufer, P., and Karsch, S.

Subjects
Physics - Accelerator Physics, Physics - Plasma Physics
Abstract

We present experimental results on a plasma wakefield accelerator (PWFA) driven by high-current electron beams from a laser wakefield accelerator (LWFA). In this staged setup stable and high quality (low divergence and low energy spread) electron beams are generated at an optically-generated hydrodynamic shock in the PWFA. The energy stability of the beams produced by that arrangement in the PWFA stage is comparable to both single-stage laser accelerators and plasma wakefield accelerators driven by conventional accelerators. Simulations support that the intrinsic insensitivity of PWFAs to driver energy fluctuations can be exploited to overcome stability limitations of state-of-the-art laser wakefield accelerators when adding a PWFA stage. Furthermore, we demonstrate the generation of electron bunches with energy spread and divergence superior to single-stage LW-FAs, resulting in bunches with dense phase space and an angular-spectral charge density beyond the initial drive beam parameters. These results unambiguously show that staged LWFA-PWFA can help to tailor the electron-beam quality for certain applications and to reduce the influence of fluctuating laser drivers on the electron-beam stability. This encourages further development of this new class of staged wakefield acceleration as a viable scheme towards compact, high-quality electron beam sources.

Published
2022
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7. What is going on in a laser plasma wakefield accelerator (LPWFA)? - a theoretical perspective on the hybrid concept

Author

(0000-0001-7990-9564) Pausch, R., (0000-0002-8258-3881) Bussmann, M., Assmann, R. W., Corde, S., Couperus Cabadağ, J., Chang, Y.-Y., Ding, H., Döpp, A., Gilljohann, M. F., Götzfried, J., Heinemann, T., Hidding, B., Karsch, S., (0000-0001-9759-1166) Köhler, A., Kononenko, O., Kurz, T., Martinez De La Ossa, A., Raj, G., (0000-0002-2769-4749) Schöbel, S., (0000-0001-8965-1149) Steiniger, K., Schindler, S., (0000-0003-4362-3438) Zarini, O., (0000-0002-4626-0049) Irman, A., (0000-0003-0390-7671) Schramm, U., (0000-0002-3844-3697) Debus, A., (0000-0001-7990-9564) Pausch, R., (0000-0002-8258-3881) Bussmann, M., Assmann, R. W., Corde, S., Couperus Cabadağ, J., Chang, Y.-Y., Ding, H., Döpp, A., Gilljohann, M. F., Götzfried, J., Heinemann, T., Hidding, B., Karsch, S., (0000-0001-9759-1166) Köhler, A., Kononenko, O., Kurz, T., Martinez De La Ossa, A., Raj, G., (0000-0002-2769-4749) Schöbel, S., (0000-0001-8965-1149) Steiniger, K., Schindler, S., (0000-0003-4362-3438) Zarini, O., (0000-0002-4626-0049) Irman, A., (0000-0003-0390-7671) Schramm, U., and (0000-0002-3844-3697) Debus, A.

Abstract

The combination of laser wakefield acceleration (LWFA) with plasma wakefield acceleration (PWFA) provides a miniaturized testbed for the study of PWFA. Since the first experimental implementation of this hybrid concept, various driver generation methods and witness injection have been investigated. Extensive simulation studies accompanied these experiments and provided insights into the complex interplay between the individual stages and the processes occurring within them. This real-world implementation allowed us to revisit and refine the original concepts. Here we present this revised implementation guide for LPWFA. Derived from these simulation campaigns, we present a theoretical analysis of the processes relevant to LPWFA hybrid accelerators. Requirements and possible methods for generating a driver package in the LWFA stage are discussed, and different laser extraction techniques are compared. The driver evolution in the PWFA stage is studied and the implications for performance limits relevant to current experiments are discussed. Different witness generation methods are also compared in terms of reproducibility and beam quality. The analysis is based on 3D3V particle-in-cell simulations performed with PIConGPU. Its 3D capability and efficiency allows studying non-rotational effects such as oblique density profiles of shocks and higher laser modes originating from experimental measurements. Their influences are briefly discussed, as well as general requirements on start-to-end simulations.

Published
2023

8. Progress in Hybrid Plasma Wakefield Acceleration

Author

(0000-0002-5827-0041) Hidding, B., (0000-0003-3440-7717) Assmann, R., (0000-0002-8258-3881) Bussmann, M., (0000-0003-0459-6326) Campbell, D., (0000-0003-0548-3999) Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-2913-5729) Döpp, A., Gilljohann, M., Götzfried, J., (0000-0002-5886-0834) Moritz Foerster, F., (0000-0001-8297-0198) Haberstroh, F., (0000-0003-2108-8702) Habib, F., (0000-0001-7747-1650) Heinemann, T., Hollatz, D., (0000-0002-4626-0049) Irman, A., Kaluza, M., (0000-0003-0746-0731) Karsch, S., (0000-0003-1757-0985) Kononenko, O., (0000-0001-7289-9228) Knetsch, A., (0000-0003-0340-9963) Kurz, T., Kuschel, S., (0000-0001-9759-1166) Köhler, A., Martinez De La Ossa, A., Nutter, A., (0000-0001-7990-9564) Pausch, R., Raj, G., (0000-0003-0390-7671) Schramm, U., (0000-0002-2769-4749) Schöbel, S., Seidel, A., (0000-0001-8965-1149) Steiniger, K., (0000-0002-6463-5406) Ufer, P., Yeung, M., (0000-0003-4362-3438) Zarini, O., Zepf, M., (0000-0002-5827-0041) Hidding, B., (0000-0003-3440-7717) Assmann, R., (0000-0002-8258-3881) Bussmann, M., (0000-0003-0459-6326) Campbell, D., (0000-0003-0548-3999) Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-2913-5729) Döpp, A., Gilljohann, M., Götzfried, J., (0000-0002-5886-0834) Moritz Foerster, F., (0000-0001-8297-0198) Haberstroh, F., (0000-0003-2108-8702) Habib, F., (0000-0001-7747-1650) Heinemann, T., Hollatz, D., (0000-0002-4626-0049) Irman, A., Kaluza, M., (0000-0003-0746-0731) Karsch, S., (0000-0003-1757-0985) Kononenko, O., (0000-0001-7289-9228) Knetsch, A., (0000-0003-0340-9963) Kurz, T., Kuschel, S., (0000-0001-9759-1166) Köhler, A., Martinez De La Ossa, A., Nutter, A., (0000-0001-7990-9564) Pausch, R., Raj, G., (0000-0003-0390-7671) Schramm, U., (0000-0002-2769-4749) Schöbel, S., Seidel, A., (0000-0001-8965-1149) Steiniger, K., (0000-0002-6463-5406) Ufer, P., Yeung, M., (0000-0003-4362-3438) Zarini, O., and Zepf, M.

Abstract

Plasma wakefield accelerators can be driven either by intense laser pulses (LWFA) or by intense particle beams (PWFA). A third approach that combines the complementary advantages of both types of plasma wakefield accelerator has been established with increasing success over the last decade and is called hybrid LWFA→PWFA. Essentially, a compact LWFA is exploited to produce an energetic, high-current electron beam as a driver for a subsequent PWFA stage, which, in turn, is exploited for phase-constant, inherently laser-synchronized, quasi-static acceleration over extended acceleration lengths. The sum is greater than its parts: the approach not only provides a compact, cost-effective alternative to linac-driven PWFA for exploitation of PWFA and its advantages for acceleration and high-brightness beam generation, but extends the parameter range accessible for PWFA and, through the added benefit of co-location of inherently synchronized laser pulses, enables high-precision pump/probing, injection, seeding and unique experimental constellations, e.g., for beam coordination and collision experiments. We report on the accelerating progress of the approach achieved in a series of collaborative experiments and discuss future prospects and potential impact.

Published
2023

9. Measuring spatio-temporal couplings using modal spatio-spectral wavefront retrieval

Author

Weisse, N, Esslinger, J, Howard, S, Foerster, FM, Haberstroh, F, Doyle, L, Norreys, P, Schreiber, J, Karsch, S, and Döpp, A

Subjects
FOS: Physical sciences, Atomic and Molecular Physics, and Optics, Optics (physics.optics), Physics - Optics
Abstract

Knowledge of spatio-temporal couplings such as pulse-front tilt or curvature is important to determine the focused intensity of high-power lasers. Common techniques to diagnose these couplings are either qualitative or require hundreds of measurements. Here we present both a new algorithm for retrieving spatio-temporal couplings, as well as novel experimental implementations. Our method is based on the expression of the spatio-spectral phase in terms of a Zernike-Taylor basis, allowing us to directly quantify the coefficients for common spatio-temporal couplings. We take advantage of this method to perform quantitative measurements using a simple experimental setup, consisting of different bandpass filters in front of a Shack-Hartmann wavefront sensor. This fast acquisition of laser couplings using narrowband filters, abbreviated FALCON, is easy and cheap to implement in existing facilities. To this end, we present a measurement of spatio-temporal couplings at the ATLAS-3000 petawatt laser using our technique.

Published
2023

12. Stable and High-Quality Electron Beams from Staged Laser and Plasma Wakefield Accelerators

Author

Foerster, F. M., primary, Döpp, A., additional, Haberstroh, F., additional, Grafenstein, K. v., additional, Campbell, D., additional, Chang, Y.-Y., additional, Corde, S., additional, Couperus Cabadağ, J. P., additional, Debus, A., additional, Gilljohann, M. F., additional, Habib, A. F., additional, Heinemann, T., additional, Hidding, B., additional, Irman, A., additional, Irshad, F., additional, Knetsch, A., additional, Kononenko, O., additional, Martinez de la Ossa, A., additional, Nutter, A., additional, Pausch, R., additional, Schilling, G., additional, Schletter, A., additional, Schöbel, S., additional, Schramm, U., additional, Travac, E., additional, Ufer, P., additional, and Karsch, S., additional

Published
2022
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13. Effect of driver charge on wakefield characteristics in a plasma accelerator probed by femtosecond shadowgraphy

Author

Schöbel, S, Schöbel, S, Pausch, R, Chang, YY, Corde, S, Couperus Cabadağ, J, Debus, A, Ding, H, Döpp, A, Foerster, FM, Gilljohann, M, Haberstroh, F, Heinemann, T, Hidding, B, Karsch, S, Köhler, A, Kononenko, O, Kurz, T, Nutter, A, Steiniger, K, Ufer, P, Martinez de la Ossa, A, Schramm, U, Irman, A, Schöbel, S, Schöbel, S, Pausch, R, Chang, YY, Corde, S, Couperus Cabadağ, J, Debus, A, Ding, H, Döpp, A, Foerster, FM, Gilljohann, M, Haberstroh, F, Heinemann, T, Hidding, B, Karsch, S, Köhler, A, Kononenko, O, Kurz, T, Nutter, A, Steiniger, K, Ufer, P, Martinez de la Ossa, A, Schramm, U, and Irman, A

Abstract

We report on experimental investigations of plasma wave structures in a plasma wakefield acceleration (PWFA) stage which is driven by electron beams from a preceding laser plasma accelerator. Femtosecond optical probing is utilized to allow for direct visualization of the plasma dynamics inside the target. We compare two regimes in which the driver propagates either through an initially neutral gas, or a preformed plasma. In the first case, plasma waves are observed that quickly damp after a few oscillations and are located within a narrow plasma channel ionized by the driver, having about the same transverse size as the plasma wakefield cavities. In contrast, for the latter robust cavities are recorded sustained over many periods. Furthermore, here an elongation of the first cavity is measured, which becomes stronger with increasing driver beam charge. Since the cavity length is linked to the maximum accelerating field strength, this elongation implies an increased field strength. This observation is supported by 3D particle-in-cell simulations performed with PIConGPU. This work can be extended for the investigation of driver depletion by probing at different propagation distances inside the plasma, which is essential for the development of high energy efficiency PWFAs.

Published
2022

14. How gullible are web measurement tools?

Author

Bianchi, G., Krumnow, B., Jonker, H.L., Karsch, S., Bianchi, G., Krumnow, B., Jonker, H.L., and Karsch, S.

Abstract

CoNEXT '22, Contains fulltext : 287473.pdf (Publisher’s version ) (Closed access)

Published
2022

15. Gas-dynamic density downramp injection in a beam-driven plasma wakefield accelerator

Author

(0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0001-7990-9564) Pausch, R., (0000-0002-2769-4749) Schöbel, S., (0000-0002-8258-3881) Bussmann, M., (0000-0003-0548-3999) Chang, Y.-Y., Corde, S., (0000-0002-3844-3697) Debus, A., Ding, H., Dopp, A., Foerster, F. M., Gilljohann, M., Haberstroh, F., Heinemann, T., Hidding, B., Karsch, S., (0000-0001-9759-1166) Köhler, A., Kononenko, O., Knetsch, A., Kurz, T., Martinez De La Ossa, A., Nutter, A., Raj, G., (0000-0001-8965-1149) Steiniger, K., (0000-0003-0390-7671) Schramm, U., (0000-0002-6463-5406) Ufer, P., (0000-0002-4626-0049) Irman, A., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0001-7990-9564) Pausch, R., (0000-0002-2769-4749) Schöbel, S., (0000-0002-8258-3881) Bussmann, M., (0000-0003-0548-3999) Chang, Y.-Y., Corde, S., (0000-0002-3844-3697) Debus, A., Ding, H., Dopp, A., Foerster, F. M., Gilljohann, M., Haberstroh, F., Heinemann, T., Hidding, B., Karsch, S., (0000-0001-9759-1166) Köhler, A., Kononenko, O., Knetsch, A., Kurz, T., Martinez De La Ossa, A., Nutter, A., Raj, G., (0000-0001-8965-1149) Steiniger, K., (0000-0003-0390-7671) Schramm, U., (0000-0002-6463-5406) Ufer, P., and (0000-0002-4626-0049) Irman, A.

Abstract

We present the experimental demonstration of density downramp injection at a gas-dynamic shock in a beam-driven plasma accelerator. The ultrashort driver electron beam with a peak-current exceeding 10 kA allows operation in the blowout regime and enables injection of electron witness bunches at gentle density ramps, i.e. longer than the plasma wavelength, which nurtures prospects for ultralow bunch emittance. By precision control over the position of injection we show that these bunches can be energy-tuned in acceleration gradients of near 120 GV/m.

Published
2022

16. Beam driven wakefield characteristics probed by femtosecond-scale shadowgraphy

Author

(0000-0002-2769-4749) Schöbel, S., (0000-0001-7990-9564) Pausch, R., Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-4713-0331) Ding, H., (0000-0003-2913-5729) Döpp, A., (0000-0002-5886-0834) Förster, M., Gilljohann, M., Haberstroh, F., (0000-0001-7747-1650) Heinemann, T., (0000-0002-5827-0041) Hidding, B., (0000-0003-0746-0731) Karsch, S., (0000-0001-9759-1166) Köhler, A., (0000-0003-1757-0985) Kononenko, O., Nutter, A., (0000-0001-8965-1149) Steiniger, K., Ufer, P., (0000-0001-8158-0980) Martinez De La Ossa, A., (0000-0003-0390-7671) Schramm, U., (0000-0002-4626-0049) Irman, A., (0000-0002-2769-4749) Schöbel, S., (0000-0001-7990-9564) Pausch, R., Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-4713-0331) Ding, H., (0000-0003-2913-5729) Döpp, A., (0000-0002-5886-0834) Förster, M., Gilljohann, M., Haberstroh, F., (0000-0001-7747-1650) Heinemann, T., (0000-0002-5827-0041) Hidding, B., (0000-0003-0746-0731) Karsch, S., (0000-0001-9759-1166) Köhler, A., (0000-0003-1757-0985) Kononenko, O., Nutter, A., (0000-0001-8965-1149) Steiniger, K., Ufer, P., (0000-0001-8158-0980) Martinez De La Ossa, A., (0000-0003-0390-7671) Schramm, U., and (0000-0002-4626-0049) Irman, A.

Abstract

High peak current electron beams from laser wakefield accelerators (LWFA) are capable to drive a particle driven wakefield (PWFA) in a subsequent stage. The intrinsic short duration of these driver beams opens the possibility for PWFA studies in a higher density regime of the order of 1018·cm-3. Since optical probing provides a reasonable contrast at this density range, direct insight into the particle-driven wakefields is possible. Here we present the results of femtosecond optical probing of such beam driven wakefields, showing pronounced differences in the morphology of beam driven plasma waves when surrounded by either neutral gas or a broad pre-generated plasma channel. Moreover, the shape and size of the first cavity of the wakefields correlates with the driver beam charge. The experimental results are supported by 3D particle-in-cell simulations performed with PIConGPU. This method can be extended to a detailed study of driver charge depletion by probing the evolution of the wakefield as it propagates through the plasma. This is an important step for further understanding and optimization of high energy efficiency PWFAs.

Published
2022

17. Demonstration of Trojan horse injection in a hybrid LWFA-driven PWFA

Author

(0000-0002-6463-5406) Ufer, P., Nutter, A., Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-2913-5729) Döpp, A., (0000-0002-5886-0834) Moritz Foerster, F., Gilljohann, M., (0000-0001-7747-1650) Heinemann, T., (0000-0002-5827-0041) Hidding, B., (0000-0003-0746-0731) Karsch, S., (0000-0001-9759-1166) Köhler, A., (0000-0003-1757-0985) Kononenko, O., (0000-0001-7990-9564) Pausch, R., (0000-0002-2769-4749) Schöbel, S., (0000-0001-8158-0980) Martinez De La Ossa, A., (0000-0003-0390-7671) Schramm, U., (0000-0002-4626-0049) Irman, A., (0000-0002-6463-5406) Ufer, P., Nutter, A., Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-2913-5729) Döpp, A., (0000-0002-5886-0834) Moritz Foerster, F., Gilljohann, M., (0000-0001-7747-1650) Heinemann, T., (0000-0002-5827-0041) Hidding, B., (0000-0003-0746-0731) Karsch, S., (0000-0001-9759-1166) Köhler, A., (0000-0003-1757-0985) Kononenko, O., (0000-0001-7990-9564) Pausch, R., (0000-0002-2769-4749) Schöbel, S., (0000-0001-8158-0980) Martinez De La Ossa, A., (0000-0003-0390-7671) Schramm, U., and (0000-0002-4626-0049) Irman, A.

Abstract

In a hybrid LWFA-driven PWFA (LPWFA) electron beams from a laser wakefield acceleration (LWFA) stage are utilized to drive a plasma wave in a subsequent plasma wakefield acceleration (PWFA) stage for acceleration of witness electron bunches to high energies. This concept allows for the exploration of PWFA-physics in a compact setup and harnessing the advantages of both plasma acceleration schemes in order to generate high-quality electron beams. Here we present results of Trojan horse injection in this hybrid plasma acceleration configuration. The DRACO laser is focused onto a gas target (LWFA stage), creating a plasma wakefield to accelerate a high peak current electron bunch. While such a beam is propagating in the second gas jet (PWFA stage), consisting of a mixture of high and low ionization threshold gas, an auxiliary low energy laser pulse intercepts the generated wakefield perpendicularly to release electrons from the highest ionization level in the first cavity. The generated witness beams show improved beam quality, such as lower energy spread compared to the drive electron beam. The realization of Trojan horse injection in LPWFA is a further step towards applications based on high brightness electron beams such as free electron lasers.

Published
2022

18. Investigating novel hybrid LPWFA accelerators using start-to-end PIConGPU simulations

Author

(0000-0001-7990-9564) Pausch, R., Couperus, J. P., Schoebel, S., Steiniger, K., Bussmann, M., Chang, Y. Y., Ding, H., Döpp, A., Foerster, M., Gilljohann, M. F., Haberstroh, F., Heinmann, T., Knetsch, A., Köhler, A., Kononenko, O., Kurz, T., Nutter, A., Raj, G., Ufer, P., Corde, S., Hidding, B., Karsch, S., Martinez De La Ossa, A., Assmann, R., Schramm, U., Irman, A., Debus, A., (0000-0001-7990-9564) Pausch, R., Couperus, J. P., Schoebel, S., Steiniger, K., Bussmann, M., Chang, Y. Y., Ding, H., Döpp, A., Foerster, M., Gilljohann, M. F., Haberstroh, F., Heinmann, T., Knetsch, A., Köhler, A., Kononenko, O., Kurz, T., Nutter, A., Raj, G., Ufer, P., Corde, S., Hidding, B., Karsch, S., Martinez De La Ossa, A., Assmann, R., Schramm, U., Irman, A., and Debus, A.

Abstract

The use of accelerated electrons from a laser wakefield accelerator (LWFA) as drivers of a plasma wakefield stage (PWFA) provides compact PWFAs that can serve as a test bed for the efficient investigation and optimization of PWFAs and their development into brightness boosters. Such hybrid accelerators have been experimentally realized at HZDR and LMU to study novel injection schemes. To better understand the microscopic, nonlinear dynamic of these accelerators, the experiments were accompanied by 3D3V particle-in-cell simulations using PIConGPU. Here, we present the latest results from these numerical studies, covering injections due to hydrodynamic shocks, beam self-modulation and breakup, and cavity elongation - all accompanied by synthetic diagnostic methods that allow direct comparison with experimental measurements. Challenges such as parasitic injections, shock injections, and non-ideal driver beam dynamics will be discussed. Recent technical advances in PIConGPU that enabled the execution of these large-scale simulation campaigns are briefly covered, as well as new synthetic in situ shadowgraph and radiation diagnostics.

Published
2022

19. Experimental results of Trojan horse injection in a hybrid LPWFA

Author

(0000-0002-6463-5406) Ufer, P., Nutter, A., Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-2913-5729) Döpp, A., (0000-0001-7747-1650) Heinemann, T., (0000-0002-5827-0041) Hidding, B., Gilljohann, M., (0000-0003-0746-0731) Karsch, S., (0000-0001-9759-1166) Köhler, A., (0000-0003-1757-0985) Kononenko, O., (0000-0001-7990-9564) Pausch, R., (0000-0002-2769-4749) Schöbel, S., (0000-0001-8158-0980) Martinez De La Ossa, A., (0000-0003-0390-7671) Schramm, U., (0000-0002-4626-0049) Irman, A., (0000-0002-6463-5406) Ufer, P., Nutter, A., Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-2913-5729) Döpp, A., (0000-0001-7747-1650) Heinemann, T., (0000-0002-5827-0041) Hidding, B., Gilljohann, M., (0000-0003-0746-0731) Karsch, S., (0000-0001-9759-1166) Köhler, A., (0000-0003-1757-0985) Kononenko, O., (0000-0001-7990-9564) Pausch, R., (0000-0002-2769-4749) Schöbel, S., (0000-0001-8158-0980) Martinez De La Ossa, A., (0000-0003-0390-7671) Schramm, U., and (0000-0002-4626-0049) Irman, A.

Abstract

A hybrid (LPWFA) plasma accelerator combines the two schemes of plasma acceleration, using a laser (LWFA) and an electron beam (PWFA) to drive the plasma wave, with the goal to combine the advantages of both methods. This concept allows studies of PWFA-physics in compact setups as well as generating high-quality electron beams to fulfill the demands of secondary light sources like FELs. We present experimental results from hybrid plasma accelerators using plasma cathode injection also known as Trojan horse injection. A short-pulsed laser is used as the injector in the second stage of the accelerator propagating perpendicular to the electron beam. When timed such, that injector laser and the first cavity of the wakefield overlap, the creation of low-energy-spread witness beams have been observed.

Published
2022

20. Excitation of beam driven plasma waves in a hybrid LPWFA

Author

(0000-0002-2769-4749) Schöbel, S., (0000-0001-7990-9564) Pausch, R., Carstens, F.-O., Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-4713-0331) Ding, H., (0000-0003-2913-5729) Döpp, A., (0000-0001-7747-1650) Heinemann, T., (0000-0002-5827-0041) Hidding, B., Gilljohann, M., (0000-0003-0746-0731) Karsch, S., (0000-0001-9759-1166) Köhler, A., (0000-0003-1757-0985) Kononenko, O., Nutter, A., Ufer, P., (0000-0001-8158-0980) Martinez De La Ossa, A., (0000-0003-0390-7671) Schramm, U., (0000-0002-4626-0049) Irman, A., (0000-0002-2769-4749) Schöbel, S., (0000-0001-7990-9564) Pausch, R., Carstens, F.-O., Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-4713-0331) Ding, H., (0000-0003-2913-5729) Döpp, A., (0000-0001-7747-1650) Heinemann, T., (0000-0002-5827-0041) Hidding, B., Gilljohann, M., (0000-0003-0746-0731) Karsch, S., (0000-0001-9759-1166) Köhler, A., (0000-0003-1757-0985) Kononenko, O., Nutter, A., Ufer, P., (0000-0001-8158-0980) Martinez De La Ossa, A., (0000-0003-0390-7671) Schramm, U., and (0000-0002-4626-0049) Irman, A.

Abstract

High peak current electron beams from laser wakefield accelerators (LWFA) are capable to drive a particle driven wakefield (PWFA) in a subsequent stage. The intrinsic short duration of these driver beams opens the possibility for PWFA studies in a higher density regime of the order of 1018·cm-3. Since optical probing provides a reasonable contrast at this density range, direct insight into the particle-driven wakefields is possible. Here we present the results of femtosecond optical probing of such beam driven wakefields, showing pronounced differences in the morphology of beam driven plasma waves when surrounded by either neutral gas or a broad pre-generated plasma channel. Moreover, the shape and size of the first cavity of the wakefields correlates with the driver beam charge. The experimental results are supported by 3D particle-in-cell simulations performed with PIConGPU. This method can be extended to a detailed study of driver charge depletion by probing the evolution of the wakefield as it propagates through the plasma. This is an important step for further understanding and optimization of high energy efficiency PWFAs.

Published
2022

21. Simulating hybrid laser-plasma wakefield accelerators using PIConGPU

Author

(0000-0001-7990-9564) Pausch, R., Couperus, J. P., Schöbel, S., Bastrakov, S., Chang, Y.-Y., Corde, S., Ding, H., Döpp, A., Foester, F. M., Gilljohann, M., Haberstroh, F., Heinemann, T., Hidding, B., Karsch, S., Koehler, A., Kononenko, O., Knetsch, A., Kurz, T., Martines De Las Ossa, A., Nutter, A., Raj, G., Steiniger, K., Schramm, U., Ufer, P., Widera, R., Irmann, A., Bussmann, M., Debus, A., (0000-0001-7990-9564) Pausch, R., Couperus, J. P., Schöbel, S., Bastrakov, S., Chang, Y.-Y., Corde, S., Ding, H., Döpp, A., Foester, F. M., Gilljohann, M., Haberstroh, F., Heinemann, T., Hidding, B., Karsch, S., Koehler, A., Kononenko, O., Knetsch, A., Kurz, T., Martines De Las Ossa, A., Nutter, A., Raj, G., Steiniger, K., Schramm, U., Ufer, P., Widera, R., Irmann, A., Bussmann, M., and Debus, A.

Abstract

An LPWFA accelerator uses electrons from a laser wakefield accelerator stage to drive a second plasma wakefield accelerator stage. This approach makes it possible to downscale PWFAs from kilometer-sized facilities to tabletop experiments and makes the improved beam quality of PWFAs available to LWFA laboratories. The experimental realization of the hybrid accelerator at HZDR was accompanied by a simulation campaign with the fully GPU accelerated, 3D3V particle-in-cell PIConGPU. Running simulations on modern GPUs allowed reducing simulation time while modeling different experimental settings in a fully three-dimensional setup. The latter enabled studying the influence of tilted shock fronts and few-cycle probes, among others. In this talk, we will not only introduce the general concept but also discuss some of the recent results obtained using particle-in-cell simulations. Moreover, the technical innovations in PIConGPU that have enabled these new types of simulations will also be briefly addressed.

Published
2022

22. Effect of driver charge on wakefield characteristics in a plasma accelerator probed by femtosecond shadowgraphy

Author

(0000-0002-2769-4749) Schöbel, S., (0000-0001-7990-9564) Pausch, R., (0000-0003-0548-3999) Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-4713-0331) Ding, H., (0000-0003-2913-5729) Döpp, A., (0000-0002-5886-0834) Moritz Foerster, F., Gilljohann, M., Haberstroh, F., (0000-0001-7747-1650) Heinemann, T., (0000-0002-5827-0041) Hidding, B., (0000-0003-0746-0731) Karsch, S., (0000-0001-9759-1166) Köhler, A., (0000-0003-1757-0985) Kononenko, O., (0000-0003-0340-9963) Kurz, T., Nutter, A., (0000-0001-8965-1149) Steiniger, K., (0000-0002-6463-5406) Ufer, P., (0000-0001-8158-0980) Martinez De La Ossa, A., (0000-0003-0390-7671) Schramm, U., (0000-0002-4626-0049) Irman, A., (0000-0002-2769-4749) Schöbel, S., (0000-0001-7990-9564) Pausch, R., (0000-0003-0548-3999) Chang, Y.-Y., (0000-0002-5015-0387) Corde, S., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-3844-3697) Debus, A., (0000-0003-4713-0331) Ding, H., (0000-0003-2913-5729) Döpp, A., (0000-0002-5886-0834) Moritz Foerster, F., Gilljohann, M., Haberstroh, F., (0000-0001-7747-1650) Heinemann, T., (0000-0002-5827-0041) Hidding, B., (0000-0003-0746-0731) Karsch, S., (0000-0001-9759-1166) Köhler, A., (0000-0003-1757-0985) Kononenko, O., (0000-0003-0340-9963) Kurz, T., Nutter, A., (0000-0001-8965-1149) Steiniger, K., (0000-0002-6463-5406) Ufer, P., (0000-0001-8158-0980) Martinez De La Ossa, A., (0000-0003-0390-7671) Schramm, U., and (0000-0002-4626-0049) Irman, A.

Abstract

We report on experimental investigations of plasma wave structures in a plasma wakefield acceleration (PWFA) stage which is driven by electron beams from a preceding laser plasma accelerator. Femtosecond optical probing is utilized to allow for direct visualization of the plasma dynamics inside the target. We compare two regimes in which the driver propagates either through an initially neutral gas, or a preformed plasma. In the first case, plasma waves are observed that quickly damp after a few oscillations and are located within a narrow plasma channel ionized by the driver, having about the same transverse size as the plasma wakefield cavities. In contrast, for the latter robust cavities are recorded sustained over many periods. Furthermore, here an elongation of the first cavity is measured, which becomes stronger with increasing driver beam charge. Since the cavity length is linked to the maximum accelerating field strength, this elongation implies an increased field strength. This observation is supported by 3D particle-in-cell simulations performed with PIConGPU. This work can be extended for the investigation of driver depletion by probing at different propagation distances inside the plasma, which is essential for the development of high energy efficiency PWFAs.

Published
2022

23. Simulating hybrid laser-plasma wakefield accelerators using PIConGPU - A look beyond the publication-ready plots

Author

(0000-0001-7990-9564) Pausch, R., Bussmann, M., Steiniger, K., Widera, R., Schöbel, S., Chang, Y.-Y., Ghaith, A., Couperus Cabadağ, J., Heinemann, T., Ding, H., Döpp, A., Gilljohann, M. F., Kononenko, O., Raj, G., Corde, S., Hidding, B., Karsch, S., Martinez De La Ossa, A., Irman, A., Schramm, U., Debus, A., (0000-0001-7990-9564) Pausch, R., Bussmann, M., Steiniger, K., Widera, R., Schöbel, S., Chang, Y.-Y., Ghaith, A., Couperus Cabadağ, J., Heinemann, T., Ding, H., Döpp, A., Gilljohann, M. F., Kononenko, O., Raj, G., Corde, S., Hidding, B., Karsch, S., Martinez De La Ossa, A., Irman, A., Schramm, U., and Debus, A.

Abstract

A review of the simulation work behind the recent LPWFA publications.

Published
2022

24. Accompanying the hybrid LPWFA experiment campaign with a computer simulation campaign: What we model, what we learn, and where we need to become better

Author

(0000-0001-8965-1149) Steiniger, K., (0000-0001-7990-9564) Pausch, R., (0000-0003-3396-6154) Bastrakov, S., (0000-0003-0548-3999) Chang, Y.-Y., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-4626-0049) Irman, A., (0000-0001-9759-1166) Köhler, A., Kurz, T., (0000-0002-2769-4749) Schöbel, S., (0000-0003-1642-0459) Widera, R., (0000-0003-0390-7671) Schramm, U., (0000-0003-4362-3438) Zarini, O., (0000-0002-3844-3697) Debus, A., (0000-0002-8258-3881) Bussmann, M., Heinemann, T., Assmann, R. W., Martinez De La Ossa, A., Hidding, B., Gilljohann, M. F., Ding, H., Götzfried, J., Schindler, S., Döpp, A., Karsch, S., Kononenko, O., Raj, G., Corde, S., (0000-0001-8965-1149) Steiniger, K., (0000-0001-7990-9564) Pausch, R., (0000-0003-3396-6154) Bastrakov, S., (0000-0003-0548-3999) Chang, Y.-Y., (0000-0001-9129-4208) Couperus Cabadağ, J. P., (0000-0002-4626-0049) Irman, A., (0000-0001-9759-1166) Köhler, A., Kurz, T., (0000-0002-2769-4749) Schöbel, S., (0000-0003-1642-0459) Widera, R., (0000-0003-0390-7671) Schramm, U., (0000-0003-4362-3438) Zarini, O., (0000-0002-3844-3697) Debus, A., (0000-0002-8258-3881) Bussmann, M., Heinemann, T., Assmann, R. W., Martinez De La Ossa, A., Hidding, B., Gilljohann, M. F., Ding, H., Götzfried, J., Schindler, S., Döpp, A., Karsch, S., Kononenko, O., Raj, G., and Corde, S.

Abstract

The Hybrid Collaboration, a joint undertaking by HZDR, DESY, University of Strathclyde, LMU, and LOA, performed hybrid LPWFA experiments which utilize electron bunches from a laser wakefield accelerator (LWFA) as drivers of a plasma wakefield stage (PWFA) to demonstrate the feasibility of compact PWFAs serving as a test bed for the efficient investigation and optimization of PWFAs and their development into brightness boosters. To better understand the microscopic, nonlinear dynamic of these accelerators, the experiments were accompanied by 3D3V particle-in-cell simulations using PIConGPU. Here, we present insights into the dynamics of the hybrid LPWFA that we gained from start-to-end simulations of the experimental setup at HZDR. These regard electron injections due to hydrodynamic shocks, beam self-modulation and breakup, and cavity elongation - all backed-up by synthetic diagnostics that allow direct comparison with experimental measurements. We discuss our approach to model these synthetic diagnostics directly within the PIConGPU simulation as well as modelling certain aspects of the experimental setup, such as the drive laser. Continuing this, the talk highlights a few recent technical advances in PIConGPU that enable better modelling of the micro-physics, experiment conditions, or signals of experiment diagnostics.

Published
2022

25. Experimental results of Trojan horse injection in a hybrid LPWFA

Author

Ufer, P., Nutter, A., Chang, Y.-Y., Corde, S., Couperus Cabadağ, J. P., Debus, A., Döpp, A., Heinemann, T., Hidding, B., Gilljohann, M., Karsch, S., Köhler, A., Kononenko, O., Pausch, R., Schöbel, S., Martinez De La Ossa, A., Schramm, U., and Irman, A.

Abstract

A hybrid (LPWFA) plasma accelerator combines the two schemes of plasma acceleration, using a laser (LWFA) and an electron beam (PWFA) to drive the plasma wave, with the goal to combine the advantages of both methods. This concept allows studies of PWFA-physics in compact setups as well as generating high-quality electron beams to fulfill the demands of secondary light sources like FELs. We present experimental results from hybrid plasma accelerators using plasma cathode injection also known as Trojan horse injection. A short-pulsed laser is used as the injector in the second stage of the accelerator propagating perpendicular to the electron beam. When timed such, that injector laser and the first cavity of the wakefield overlap, the creation of low-energy-spread witness beams have been observed.

Published
2022

26. Beam driven wakefield characteristics probed by femtosecond-scale shadowgraphy

Author

Schöbel, S., Pausch, R., Chang, Y.-Y., Corde, S., Couperus Cabadağ, J. P., Debus, A., Ding, H., Döpp, A., Förster, M., Gilljohann, M., Haberstroh, F., Heinemann, T., Hidding, B., Karsch, S., Köhler, A., Kononenko, O., Nutter, A., Steiniger, K., Ufer, P., Martinez De La Ossa, A., Schramm, U., and Irman, A.

Abstract

High peak current electron beams from laser wakefield accelerators (LWFA) are capable to drive a particle driven wakefield (PWFA) in a subsequent stage. The intrinsic short duration of these driver beams opens the possibility for PWFA studies in a higher density regime of the order of 1018·cm-3. Since optical probing provides a reasonable contrast at this density range, direct insight into the particle-driven wakefields is possible. Here we present the results of femtosecond optical probing of such beam driven wakefields, showing pronounced differences in the morphology of beam driven plasma waves when surrounded by either neutral gas or a broad pre-generated plasma channel. Moreover, the shape and size of the first cavity of the wakefields correlates with the driver beam charge. The experimental results are supported by 3D particle-in-cell simulations performed with PIConGPU. This method can be extended to a detailed study of driver charge depletion by probing the evolution of the wakefield as it propagates through the plasma. This is an important step for further understanding and optimization of high energy efficiency PWFAs.

Published
2022

27. Investigating novel hybrid LPWFA accelerators using start-to-end PIConGPU simulations

Author

Pausch, R., Couperus, J. P., Schoebel, S., Steiniger, K., Bussmann, M., Chang, Y. Y., Ding, H., Döpp, A., Foerster, M., Gilljohann, M. F., Haberstroh, F., Heinmann, T., Knetsch, A., Köhler, A., Kononenko, O., Kurz, T., Nutter, A., Raj, G., Ufer, P., Corde, S., Hidding, B., Karsch, S., Martinez De La Ossa, A., Assmann, R., Schramm, U., Irman, A., and Debus, A.

Subjects
hybrid, PIConGPU, LPWFA, LWFA, PWFA
Abstract

The use of accelerated electrons from a laser wakefield accelerator (LWFA) as drivers of a plasma wakefield stage (PWFA) provides compact PWFAs that can serve as a test bed for the efficient investigation and optimization of PWFAs and their development into brightness boosters. Such hybrid accelerators have been experimentally realized at HZDR and LMU to study novel injection schemes. To better understand the microscopic, nonlinear dynamic of these accelerators, the experiments were accompanied by 3D3V particle-in-cell simulations using PIConGPU. Here, we present the latest results from these numerical studies, covering injections due to hydrodynamic shocks, beam self-modulation and breakup, and cavity elongation - all accompanied by synthetic diagnostic methods that allow direct comparison with experimental measurements. Challenges such as parasitic injections, shock injections, and non-ideal driver beam dynamics will be discussed. Recent technical advances in PIConGPU that enabled the execution of these large-scale simulation campaigns are briefly covered, as well as new synthetic in situ shadowgraph and radiation diagnostics.

Published
2022

28. How gullible are web measurement tools?

Author

Krumnow, B., Jonker, H.L., Karsch, S., and Bianchi, G.

Subjects
Digital Security
Abstract

Contains fulltext : 287473.pdf (Publisher’s version ) (Closed access) CoNEXT '22

Published
2022

29. Excitation of beam driven plasma waves in a hybrid LPWFA

Author

Schöbel, S., Pausch, R., Carstens, F.-O., Chang, Y.-Y., Corde, S., Couperus Cabadağ, J. P., Debus, A., Ding, H., Döpp, A., Heinemann, T., Hidding, B., Gilljohann, M., Karsch, S., Köhler, A., Kononenko, O., Nutter, A., Ufer, P., Martinez De La Ossa, A., Schramm, U., and Irman, A.

Abstract

High peak current electron beams from laser wakefield accelerators (LWFA) are capable to drive a particle driven wakefield (PWFA) in a subsequent stage. The intrinsic short duration of these driver beams opens the possibility for PWFA studies in a higher density regime of the order of 1018·cm-3. Since optical probing provides a reasonable contrast at this density range, direct insight into the particle-driven wakefields is possible. Here we present the results of femtosecond optical probing of such beam driven wakefields, showing pronounced differences in the morphology of beam driven plasma waves when surrounded by either neutral gas or a broad pre-generated plasma channel. Moreover, the shape and size of the first cavity of the wakefields correlates with the driver beam charge. The experimental results are supported by 3D particle-in-cell simulations performed with PIConGPU. This method can be extended to a detailed study of driver charge depletion by probing the evolution of the wakefield as it propagates through the plasma. This is an important step for further understanding and optimization of high energy efficiency PWFAs.

Published
2022

30. Demonstration of Trojan horse injection in a hybrid LWFA-driven PWFA

Author

Ufer, P., Nutter, A., Chang, Y.-Y., Corde, S., Couperus Cabadağ, J. P., Debus, A., Döpp, A., Moritz Foerster, F., Gilljohann, M., Heinemann, T., Hidding, B., Karsch, S., Köhler, A., Kononenko, O., Pausch, R., Schöbel, S., Martinez De La Ossa, A., Schramm, U., and Irman, A.

Abstract

In a hybrid LWFA-driven PWFA (LPWFA) electron beams from a laser wakefield acceleration (LWFA) stage are utilized to drive a plasma wave in a subsequent plasma wakefield acceleration (PWFA) stage for acceleration of witness electron bunches to high energies. This concept allows for the exploration of PWFA-physics in a compact setup and harnessing the advantages of both plasma acceleration schemes in order to generate high-quality electron beams. Here we present results of Trojan horse injection in this hybrid plasma acceleration configuration. The DRACO laser is focused onto a gas target (LWFA stage), creating a plasma wakefield to accelerate a high peak current electron bunch. While such a beam is propagating in the second gas jet (PWFA stage), consisting of a mixture of high and low ionization threshold gas, an auxiliary low energy laser pulse intercepts the generated wakefield perpendicularly to release electrons from the highest ionization level in the first cavity. The generated witness beams show improved beam quality, such as lower energy spread compared to the drive electron beam. The realization of Trojan horse injection in LPWFA is a further step towards applications based on high brightness electron beams such as free electron lasers.

Published
2022

31. Simulating hybrid laser-plasma wakefield accelerators using PIConGPU

Author

Pausch, R., Couperus, J. P., Schöbel, S., Bastrakov, S., Chang, Y.-Y., Corde, S., Ding, H., Döpp, A., Foester, F. M., Gilljohann, M., Haberstroh, F., Heinemann, T., Hidding, B., Karsch, S., Koehler, A., Kononenko, O., Knetsch, A., Kurz, T., Martines De Las Ossa, A., Nutter, A., Raj, G., Steiniger, K., Schramm, U., Ufer, P., Widera, R., Irmann, A., Bussmann, M., and Debus, A.

Subjects
hybrid, accelerator, PIConGPU, LWFA, PWFA
Abstract

An LPWFA accelerator uses electrons from a laser wakefield accelerator stage to drive a second plasma wakefield accelerator stage. This approach makes it possible to downscale PWFAs from kilometer-sized facilities to tabletop experiments and makes the improved beam quality of PWFAs available to LWFA laboratories. The experimental realization of the hybrid accelerator at HZDR was accompanied by a simulation campaign with the fully GPU accelerated, 3D3V particle-in-cell PIConGPU. Running simulations on modern GPUs allowed reducing simulation time while modeling different experimental settings in a fully three-dimensional setup. The latter enabled studying the influence of tilted shock fronts and few-cycle probes, among others. In this talk, we will not only introduce the general concept but also discuss some of the recent results obtained using particle-in-cell simulations. Moreover, the technical innovations in PIConGPU that have enabled these new types of simulations will also be briefly addressed.

Published
2022

32. Pareto Optimization and Tuning of a Laser Wakefield Accelerator.

Author

Irshad F, Eberle C, Foerster FM, Grafenstein KV, Haberstroh F, Travac E, Weisse N, Karsch S, and Döpp A

Abstract

Optimization of accelerator performance parameters is limited by numerous trade-offs, and finding the appropriate balance between optimization goals for an unknown system is challenging to achieve. Here, we show that multiobjective Bayesian optimization can map the solution space of a laser wakefield accelerator (LWFA) in a very sample-efficient way. We observe that there exists a wide range of Pareto-optimal solutions that trade beam energy versus charge at similar laser-to-beam efficiency. Moreover, many applications such as light sources require particle beams at certain target energies. We demonstrate accurate energy tuning of the LWFA from 150 to 400 MeV via the simultaneous adjustment of eight parameters. To further advance this use case, we propose an inverse model that allows a user to specify desired beam parameters. Trained on the forward Gaussian process model, the inverse model generates input parameter value ranges within which the desired setting is likely to be reached. The method reveals different strategies for accelerator tuning and is expected to drastically facilitate the operation of LWFAs in the near future.

Published
2024
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33. Radiation Exposure in the Acute Phase after Aneurysmal Subarachnoid Hemorrhage in the Era of CT Perfusion.

Author

Döring K, Mielke D, Moerer O, Stamm G, Karsch S, Psychogios MN, Rohde V, and Malinova V

Subjects
Humans, Perfusion adverse effects, Retrospective Studies, Tomography, X-Ray Computed, Treatment Outcome, Radiation Exposure prevention & control, Subarachnoid Hemorrhage complications, Vasospasm, Intracranial etiology
Abstract

Purpose: Aneurysmal subarachnoid hemorrhage (aSAH) is associated with a high risk of developing multiple complications requiring further diagnostics including imaging associated with radiation exposure (RE). Since aSAH often affects younger patients, the obtained cumulative RE may have serious long-term health consequences. The aim of this study was to calculate the cumulative RE in the acute phase after aSAH and to identify contributors to RE. Additionally, we investigated whether there is a correlation of RE with outcome., Methods: A retrospective analysis of patients with aSAH treated at our department from 2012 to 2018 was performed. The radiation dose of every single cranial radiological examination was calculated for every patient. The outcome was assessed according to the modified Rankin scale (mRS) 3 months after ictus. Factors associated with high RE were evaluated and the correlation of RE with outcome was assessed., Results: In 268 included consecutive patients, the mean cumulative RE per patient was 39.95 mSv, ranging from 2 to 265.5 mSv. A higher RE correlated with delayed cerebral ischemia (r = 0.52, p < 0.0001), delayed infarction (r = 0.25, p < 0.0001), delayed ischemic neurological deficits (r = 0.29, p < 0.0001) and transcranial Doppler (TCD)-vasospasm (r = 0.34, p < 0.0001). Independent predictors of outcome were age (p = 0.0001), World Federation of Neurosurgical Societies (WFNS) grade (p < 0.0001) and delayed infarction (p = 0.0004), while RE did not correlate with outcome., Conclusion: There is a considerable imaging-related RE in aSAH patients. A meticulous decision-making process and imaging protocols with lower RE for the deployment of CT-based and fluoroscopy-based imaging is indicated in order to minimize the risk for radiation-mediated heath consequences in this patient population., (© 2021. Springer-Verlag GmbH Germany, part of Springer Nature.)

Published
2022
Full Text
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