DEVELOPMENT OF A 300 KV DC HIGH VOLTAGE PHOTOGUN AND BEAM BASED STUDIES OF ALKALI NTIMONIDE PHOTOCATHODES
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
To advance magnetized gun research in the United States, a compact DC high voltage photogun with inverted-insulator geometry was designed, built, and operated reliably at 300 kV bias voltage using alkali-antimonide photocathodes. This photogun will provide a magnetized electron beam for the future Jefferson Lab Electron-Ion Collider (JLEIC) cooler. This research describes key electrostatic design features of the photogun and evaluates the performance of the in-house fabricated photocathodes and the quality of the electron beams. The thermal emittance of the electron beam was measured with various conditions: differ?ent gun bias voltages, different laser spot sizes, and photocathodes with different substrate materials. It has been hypothesized that the photocathode surface roughness affects the quality of the photocathodes and the electron beam produced, which is directly related to the thickness of the antimony layer of the photocathode. This effect was studied experimen?tally for both the beam emittance and photocathode quantum efficiency lifetime, and the measurements indicate that the beam emittance is largely independent of the antimony layer thickness, and the lifetime benefits from a thick layer. The ion bombardment always poses a problem for the photocathodes during high current beam operations. An effective way to repel the beam-induced ions was identified and implemented, and a sustainable 28 mA beam was achieved from the gun. This thesis presents a good performance of the photogun, a remarkable quantum efficiency lifetime of the photocathodes and a low emittance of the electron beam.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 1924638
- Report Number(s):
- JLAB-ACO-18-3114; DOE/OR/23177-5715
- Country of Publication:
- United States
- Language:
- English
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