Toward a terahertz-driven electron gun

Abstract

Femtosecond electron bunches with keV energies and eV energy spread are needed by condensed matter physicists to resolve state transitions in carbon nanotubes, molecular structures, organic salts, and charge density wave materials. These semirelativistic electron sources are not only of interest for ultrafast electron diffraction, but also for electron energy-loss spectroscopy and as a seed for x-ray FELs. Thus far, the output energy spread (hence pulse duration) of ultrafast electron guns has been limited by the achievable electric field at the surface of the emitter, which is 10 MV/m for DC guns and 200 MV/m for RF guns. A single-cycle THz electron gun provides a unique opportunity to not only achieve GV/m surface electric fields but also with relatively low THz pulse energies, since a single-cycle transform-limited waveform is the most efficient way to achieve intense electric fields. Here, electron bunches of 50 fC from a flat copper photocathode are accelerated from rest to tens of eV by a microjoule THz pulse with peak electric field of 72 MV/m at 1 kHz repetition rate. We show that scaling to the readily-available GV/m THz field regime would translate to monoenergetic electron beams of ~100 keV.

16 pages, 4 figures

References in corpus (3)

• Terahertz-driven linear electron acceleration
• New electron source concept for single-shot sub-100 fs electron diffraction in the 100 keV range
• Compact electron acceleration and bunch compression in THz waveguides

Cited by in corpus (8)

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• Terahertz-driven, all-optical electron gun
• Cascaded high-gradient terahertz-driven acceleration of relativistic electron beams
• Demonstration of sub-luminal propagation of single-cycle terahertz pulses for particle acceleration
• Simultaneous electronic and the magnetic excitation of a ferromagnet by intense THz pulses
• Phase space manipulation of free-electron pulses from metal nanotips using combined THz near-fields and external biasing
• Diffraction at the Open-Ended Dielectric-Loaded Circular Waveguide: Rigorous Approach
• Diffraction at the Open End of Dielectric-Lined Circular Waveguide