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Title: Ultraviolet laser transverse profile shaping for improving x-ray free electron laser performance

Abstract

The photocathode rf gun is one of the most critical components in x-ray free electron lasers. The drive laser strikes the photocathode surface, which emits electrons with properties that depend on the shape of the drive laser. Most free electron lasers use photocathodes with work function in the ultraviolet, a wavelength where direct laser manipulation becomes challenging. In this paper, we present a novel application of a digital micromirror device (DMD) for the 253 nm drive laser at the Linear Coherent Light Source. Laser profile shaping is accomplished through an iterative algorithm that takes into account shaping error and efficiency. Next, we use laser shaping to control the X-ray laser output via an online optimizer, which shows improvement in FEL pulse energy. Lastly, as a preparation for electron beam shaping, we use the DMD to measure the photocathode quantum efficiency across cathode surface with an averaged laser rms spot size of 59 μm. In conclusion, our experiments demonstrate promising outlook of using DMD to shape ultraviolet lasers for photocathode rf guns with various applications.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1375519
Alternate Identifier(s):
OSTI ID: 1390320
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article: Published Article
Journal Name:
Physical Review Accelerators and Beams
Additional Journal Information:
Journal Volume: 20; Journal Issue: 8; Journal ID: ISSN 2469-9888
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS

Citation Formats

Li, S., Alverson, S., Bohler, D., Egger, A., Fry, A., Gilevich, S., Huang, Z., Miahnahri, A., Ratner, D., Robinson, J., and Zhou, F. Ultraviolet laser transverse profile shaping for improving x-ray free electron laser performance. United States: N. p., 2017. Web. doi:10.1103/PhysRevAccelBeams.20.080704.
Li, S., Alverson, S., Bohler, D., Egger, A., Fry, A., Gilevich, S., Huang, Z., Miahnahri, A., Ratner, D., Robinson, J., & Zhou, F. Ultraviolet laser transverse profile shaping for improving x-ray free electron laser performance. United States. doi:10.1103/PhysRevAccelBeams.20.080704.
Li, S., Alverson, S., Bohler, D., Egger, A., Fry, A., Gilevich, S., Huang, Z., Miahnahri, A., Ratner, D., Robinson, J., and Zhou, F. Thu . "Ultraviolet laser transverse profile shaping for improving x-ray free electron laser performance". United States. doi:10.1103/PhysRevAccelBeams.20.080704.
@article{osti_1375519,
title = {Ultraviolet laser transverse profile shaping for improving x-ray free electron laser performance},
author = {Li, S. and Alverson, S. and Bohler, D. and Egger, A. and Fry, A. and Gilevich, S. and Huang, Z. and Miahnahri, A. and Ratner, D. and Robinson, J. and Zhou, F.},
abstractNote = {The photocathode rf gun is one of the most critical components in x-ray free electron lasers. The drive laser strikes the photocathode surface, which emits electrons with properties that depend on the shape of the drive laser. Most free electron lasers use photocathodes with work function in the ultraviolet, a wavelength where direct laser manipulation becomes challenging. In this paper, we present a novel application of a digital micromirror device (DMD) for the 253 nm drive laser at the Linear Coherent Light Source. Laser profile shaping is accomplished through an iterative algorithm that takes into account shaping error and efficiency. Next, we use laser shaping to control the X-ray laser output via an online optimizer, which shows improvement in FEL pulse energy. Lastly, as a preparation for electron beam shaping, we use the DMD to measure the photocathode quantum efficiency across cathode surface with an averaged laser rms spot size of 59 μm. In conclusion, our experiments demonstrate promising outlook of using DMD to shape ultraviolet lasers for photocathode rf guns with various applications.},
doi = {10.1103/PhysRevAccelBeams.20.080704},
journal = {Physical Review Accelerators and Beams},
number = 8,
volume = 20,
place = {United States},
year = {Thu Aug 17 00:00:00 EDT 2017},
month = {Thu Aug 17 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevAccelBeams.20.080704

Citation Metrics:
Cited by: 1 work
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Works referenced in this record:

Femtosecond laser pulse shaping by use of microsecond radio-frequency pulses
journal, January 1994

  • Hillegas, C. W.; Tull, J. X.; Goswami, D.
  • Optics Letters, Vol. 19, Issue 10, p. 737-739
  • DOI: 10.1364/OL.19.000737