Document Type

Article

Publication Date

2022

DOI

10.1063/5.0091134

Publication Title

Review of Scientific Instruments

Volume

93

Issue

7

Pages

073303 (1-11)

Abstract

The 300 kV DC high voltage photogun at Jefferson Lab was redesigned to deliver electron beams with a much higher bunch charge and improved beam properties. The original design provided only a modest longitudinal electric field (Ez) at the photocathode, which limited the achievable extracted bunch charge. To reach the bunch charge goal of approximately few nC with 75 ps full-width at half-maximum Gaussian laser pulse width, the existing DC high voltage photogun electrodes and anode–cathode gap were modified to increase Ez at the photocathode. In addition, the anode aperture was spatially shifted with respect to the beamline longitudinal axis to minimize the beam deflection introduced by the non-symmetric nature of the inverted insulator photogun design. We present the electrostatic design of the original photogun and the modified photogun and beam dynamics simulations that predict vastly improved performance. We also quantify the impact of the photocathode recess on beam quality, where recess describes the actual location of the photocathode inside the photogun cathode electrode relative to the intended location. A photocathode unintentionally recessed/misplaced by sub-millimeter distance can significantly impact the downstream beam size.

Comments

© 2022 AIP Publishing

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in:

Wijethunga, S. A. K., Mamun, M. A., Suleiman, R., Hernandez-Garcia, C., Bullard, B., Delayen, J. R., Grames, J., Krafft, G. A., Palacios-Serrano, G., & Poelker, M. (2022). Improving the electrostatic design of the Jefferson Lab 300 kV DC photogun. Review of Scientific Instruments, 93(7), 1-11, Article 073303.

and may be found at: https://doi.org/10.1063/5.0091134

Posted with a 12 month embargo in accordance with publisher policy.

Original Publication Citation

Wijethunga, S. A. K., Mamun, M. A., Suleiman, R., Hernandez-Garcia, C., Bullard, B., Delayen, J. R., Grames, J., Krafft, G. A., Palacios-Serrano, G., & Poelker, M. (2022). Improving the electrostatic design of the Jefferson Lab 300 kV DC photogun. Review of Scientific Instruments, 93(7), 1-11, Article 073303.

ORCID

0000-0002-8765-9208 (Wijethunga), 0000-0002-8222-8740 (Delayen)

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