Simulation Study of Effects of Ionization Processes on Radiation Pressure Ion Acceleration

Han-Wei Chen^1*, Sz-Jie Lee¹, Yao-Li Liu¹, Shih-Hung Chen¹

¹Department of Physics, National Central University, Taoyuan, Taiwan

* Presenter:Han-Wei Chen, email:w4791375@gmail.com

Laser ion acceleration possesses potential to become a compact high-energy ion source for various applications, including cancer therapy, high-resolution radiography, and fast ignition fusion. Among those proposed acceleration schemes, the radiation pressure acceleration (RPA) attracts more attention due to high stability, high energy conversion efficiency, high beam quality and high energy scalability [1] – [4].

In most previous studies, a fully ionized target is pre-assumed in particle-in-cell (PIC) simulations. But ionization processes play an important role in the early stage of laser-target interaction, especially for those cases with a thicker solid target. The major goal of this work is to reveal the effect of ionization processes on the results of PRA. The field ionization model and collisional ionization model [5] - [6] are applied in the simulation.
We mainly focus on three issues:
1. The criteria for stable operations of RPA.
2. The effect of laser profiles on the quality of accelerated ion beam.
3. The energy scaling law of accelerated ion beam.

REFERENCES:
[1]B. Qiao, S. Kar, M. Geissler, P. Gibbon, M. Zepf, and M. Borghesi, Phys. Rev. Lett. 108, 115002 (2012).
[2] Henig, A., Steinke, S., Schnürer, M., Sokollik, T., Hörlein, R., Kiefer, D., ... & Habs, D. (2009). Radiation-pressure acceleration of ion beams driven by circularly polarized laser pulses. Physical Review Letters, 103(24), 245003.
[3] Yan, X. Q., Lin, C., Sheng, Z. M., Guo, Z. Y., Liu, B. C., Lu, Y. R., ... & Chen, J. E. (2008). Generating high-current monoenergetic proton beams by a circularlypolarized laser pulse in the phase-stableacceleration regime. Physical review letters, 100(13), 135003.
[4] Shen, X. F., Qiao, B., Pukhov, A., Kar, S., Zhu, S. P., Borghesi, M., & He, X. T. (2021). Scaling laws for laser-driven ion acceleration from nanometer-scale ultrathin foils. Physical Review E, 104(2), 025210.
[5]Arber, T. D., Bennett, K., Brady, C. S., Lawrence-Douglas, A., Ramsay, M. G., Sircombe, N. J., ... & Ridgers, C. P. (2015). Contemporary particle-in-cell approach to laser-plasma modelling. Plasma Physics and Controlled Fusion, 57(11), 113001.
[6] Lawrence-Douglas, A. (2013). Ionisation effects for laser-plasma interactions by particle-in-cell code (Doctoral dissertation, University of Warwick).

Keywords: laser plasma acceleration, radiation pressure acceleration (RPA), ionization process, particle-in-cell (PIC) simulation