Terahertz-Driven Nano-tip Field-Emission Electron Gun and Cascaded Acceleration

TL;DR

This paper introduces two types of terahertz-driven nanotip electron guns with reflective structures that enhance acceleration efficiency and demonstrates cascaded acceleration, paving the way for high-energy, high-quality THz electron sources.

Contribution

It presents novel reflective gun designs and experimentally verifies cascaded acceleration, advancing THz-driven electron gun technology.

Findings

SLRGs outperform SLNRGs in acceleration efficiency.

DLRGs achieve cascaded electron acceleration experimentally.

Experimental results closely match simulations.

Abstract

This paper reports two versions of terahertz (THz)-driven nanotip field-emission electron guns: single-layer reflective guns (SLRGs) and double-layer reflective guns (DLRGs). Both guns use nanotip emitters and accelerate electrons through the electric field of the THz wave. SLRGs employ a reflective structure to superimpose the initial and subsequent half-cycles of the THz electric field, enhancing the field amplitude and acceleration efficiency. Experiments have demonstrated that SLRGs achieve higher acceleration efficiency than single-layer nonreflective guns (SLNRGs) for identical THz input energies. This constitutes direct experimental verification of the efficacy of the reflective structure. Theoretically, SLRGs operating in single-feed mode can match the acceleration efficiency of dual-feed SLNRGs while reducing operational complexity. DLRGs demonstrate THz-driven cascaded electron acceleration through precise scanning of the delay between two incident THz beams. This represents a direct experimental demonstration of cascaded acceleration in THz-driven electron sources. The experimental results of DLRGs align closely with the results of electron dynamics predicted by simulations. This establishes the foundation for developing multilayer high-acceleration-efficiency THz-driven high-energy electron guns. The ability to manipulate the THz for each layer individually holds promising potential for improving the beam quality of THz electron guns.