Numerical study of high efficiency PDO-emission sources for THz-driven acceleration

이재호, 송형선, 박도현, M. Kumar, 허민섭

Recently, there has been a growing interest in enhancing compact electron accelerators for x-ray systems. One promising approach is the utilization of THz (terahertz)-driven acceleration. Conventional RF (radio-frequency) accelerators face limitations due to the vacuum breakdown threshold of the accelerator materials. For most common RF accelerators, the surface electric field typically reaches around 100 MV/m. However, THz range pulses have the potential to achieve multi-GV/m vacuum breakdown limits by increasing the operational frequency and reducing the optical pulse length. In this study, we propose a THz-driven linear electron accelerator that exploits the concept of PDO (plasma dipole oscillation) [1,2]. PDO can be generated through the interaction of two colliding lasers, causing trapped electrons in the beat wave of laser pulses to experience movement and oscillation due to electrostatic restoring forces. Additionally, we have achieved a notable conversion efficiency of approximately 1.48% using PDO, which is particularly advantageous for THz-driven accelerators since most solid-state-based THz sources struggle to achieve conversion efficiencies lower than 1%. In this presentation, we present the demonstration of THz-driven acceleration through PIC (particle-in-cell) simulation and introduce the concept of PDO, along with its corresponding results. 

[1] Kwon, Kyu Been, et al. "High-energy, short-duration bursts of coherent terahertz radiation from an embedded plasma dipole." Scientific Reports 8.1 (2018): 145. 

[2] Lee, Jaeho, et al. "Intense narrowband terahertz pulses produced by obliquely colliding laser pulses in helium gas." Physics of Plasmas 30.4 (2023).