THz-Driven Electron Acceleration by Utilizing PDO-THz Emission

 J. Lee, H. S. Song, D. Park, M. Kumar, M. S. Hur

The vacuum break threshold of accelerator structure used in conventional RF (radio-frequency) accelerators limits their operation. The electric field on the surface of a standard RF accelerator is typically close to 30 ~ 50 MV/m according to experimental estimates () where  is the surface electric field,  is the frequency of operation,  is the pulse length. However, pulses in the THz (terahertz) range (1~10 THz) have the potential to exceed the multi-GV/m vacuum breaking limit by increasing the operating frequency and reducing the pulse length [3]. Here, we propose the use of a novel THz source called PDO (plasma dipole oscillation) [1-2] for terahertz-based electron acceleration. PDO can be produced through two colliding lasers of different frequency, occurring trapped electrons in the beat potential of laser pulses to undergo displacement of electron bunch and oscillation due to electrostatic restoring forces. This novel of THz-sources can be powerful for THz-driven acceleration because it has relatively narrowband spectrum and high conversion efficiency (~1.48%), also high electric field gradient (~1.5 GV/m). After setting up an accelerating structure with a horn-like waveguide in new simulation, we were able to demonstrate appropriate THz pulses of PDO. In this presentation, we discuss new simulation results of PDO-THz driven acceleration.

[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).

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

[3] Nanni, Emilio A, et al. "Terahertz-driven linear electron acceleration." Nat. Commun. 6, 8486 (2015).