Cascaded high-gradient terahertz-driven acceleration of relativistic electron beams

Abstract

Terahertz (THz)-driven acceleration has recently emerged as a new route for delivering ultrashort bright electron beams efficiently, reliably, and in a compact setup. Many THz-driven acceleration related working schemes and key technologies have been successfully demonstrated and are continuously being improved to new limits. However, the achieved acceleration gradient and energy gain remain low, and the potential physics and technical challenges in the high field and high energy regime are still under-explored. Here we report a record energy gain of 170 keV in a single-stage configuration, and demonstrate the first cascaded acceleration of a relativistic beam with a 204 keV energy gain in a two-stages setup. Whole-bunch acceleration is accomplished with an average accelerating gradient of 85 MV/m and a peak THz electric field of 1.1 GV/m. This proof-of-principle result is a crucial advance in THz-driven acceleration with a major impact on future electron sources and related scientific discoveries.

Towards High-Repetition-Rate Intense Terahertz Source With Metal Wire-Based Plasma

“…5, The wire diameter, length, and port frequency are set respectively to 80 𝜇𝑚 , 5 cm and 0.3THz, being consistent with the experimental parameters. By using a quasi- For its radial polarization feature, this THz source has the potential to be directly used in THz dielectric waveguide electron acceleration [8,34].…”

“…The radial electric field and angular magnetic field indicate that the THz wave is TM01 mode as shown in Fig.5(e). For its radial polarization feature, this THz source has the potential to be directly used in THz dielectric waveguide electron acceleration[8,34].…”

Stable and scalable multistage terahertz-driven particle accelerator

“…S1). A horn with an opening angle of 10 degrees is attached to the DLW to increase the coupling efficiency [15,20,21], which is measured to be about 70% in this experiment. An optical image of the mini-accelerator is shown in Fig.…”

“…However, the large size and cost of conventional accelerators based on radio-frequency (rf) technology limit accessibility and are motivating development of compact accelerators . Among the techniques, terahertz (THz)-driven acceleration has great potential [15][16][17][18][19][20][21]. Compared to the rf accelerator, the approximately 100-fold reduction in wavelength for the THz accelerator promises significant reduction in size, but increase in breakdown threshold to the gigaelectronvoltper-meter regime [22,23].…”

“…However, with the electron beam being longer than half of the THz wavelength, only a fraction of the electrons are accelerated by a laser-generated THz pulse, while others are decelerated [15][16][17][18][19]. Though recently, the staging of acceleration for relativistic electrons has been reported [21], the short acceleration length from an accelerator-produced single-cycle transition radiation THz pulse and the limited beam quality is not sufficient to address the question of whether an electron bunch can be stably accelerated in successive long structures with high charge coupling efficiency and high stability. We note that while whole-bunch acceleration for keV electron beam in two stages has been reported in [20], the small energy gain and large energy spread of the beam makes it difficult to answer the question of whether beam energy spread can be preserved in staged acceleration with considerable energy gain.…”