Grid pulser for an electron gun with a thermionic cathode for the high-power operation of a terahertz free-electron laser

Shoji Suemine, Keigo Kawase, Naoya Sugimoto, Shigeru Kashiwagi, Kazuya Furukawa, Ryukou Kato, Akinori Irizawa, Masaki Fujimoto, Hiroki Ohsumi, Masaki Yaguchi, Sousuke Funakoshi, Ryouta Tsutsumi, Kumiko Kubo, Akira Tokuchi, Goro Isoyama

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

A grid pulser for a thermionic-cathode electron gun for an L-band electron linac with an RF frequency of 1.3 GHz was developed in an effort to increase the power of a terahertz (THz) free-electron laser (FEL) based on the linac. The grid pulser can generate a train of electron pulses with a 5-ns duration at intervals of 36.9 ns or at a repetition frequency of 27 MHz, which is the 48th sub-harmonic of the RF frequency, and with a peak current of up to 2.4 A or higher, which is four times higher than the current that can be obtained with the conventional grid pulser. In combination with the sub-harmonic buncher (SHB) system, whose fundamental frequency is 108 MHz (the 12th sub-harmonic of the RF frequency), an electron beam that comprises electron bunches separated by 36.9-ns intervals for a period of 8 μs can be successfully accelerated using the linac to an energy of 15 MeV under the condition that the average beam current or, correspondingly, the beam loading in the acceleration tube of the linac is the same as that obtained using the conventional grid pulser. The time-resolved energy spectrum indicates that the energy is constant over the latter 6 μs and that the energy spread is 1.2% (FWHM); this performance satisfies the requirements for the FEL. The bunch charge measured at the end of the FEL beamline is 4 nC, which is four times higher than that obtained using the conventional grid pulser.

Original languageEnglish
Pages (from-to)97-103
Number of pages7
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Volume773
DOIs
Publication statusPublished - 2015 Aug 6

Keywords

  • Electron linear accelerator
  • Free-electron lasers
  • Thermionic cathode

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation

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