skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Structured photocathodes for improved high-energy x-ray efficiency in streak cameras

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1417269
Report Number(s):
LLNL-CONF-740942
Journal ID: ISSN 0034--6748
DOE Contract Number:
AC52-07NA27344
Resource Type:
Conference
Resource Relation:
Journal Volume: 87; Journal Issue: 11; Conference: Presented at: High-Temperature Plasma Diagnostics, Madison, WI, United States, Jun 05 - Jun 09, 2016
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY

Citation Formats

Opachich, Y P, Bell, P M, Bradley, D K, Chen, N, Feng, J, Gopal, A, Hatch, B, Hilsabeck, T J, Huffman, E, Koch, J A, Landen, O L, MacPhee, A G, Nagel, S R, and Udin, S. Structured photocathodes for improved high-energy x-ray efficiency in streak cameras. United States: N. p., 2017. Web. doi:10.1063/1.4961302.
Opachich, Y P, Bell, P M, Bradley, D K, Chen, N, Feng, J, Gopal, A, Hatch, B, Hilsabeck, T J, Huffman, E, Koch, J A, Landen, O L, MacPhee, A G, Nagel, S R, & Udin, S. Structured photocathodes for improved high-energy x-ray efficiency in streak cameras. United States. doi:10.1063/1.4961302.
Opachich, Y P, Bell, P M, Bradley, D K, Chen, N, Feng, J, Gopal, A, Hatch, B, Hilsabeck, T J, Huffman, E, Koch, J A, Landen, O L, MacPhee, A G, Nagel, S R, and Udin, S. Tue . "Structured photocathodes for improved high-energy x-ray efficiency in streak cameras". United States. doi:10.1063/1.4961302. https://www.osti.gov/servlets/purl/1417269.
@article{osti_1417269,
title = {Structured photocathodes for improved high-energy x-ray efficiency in streak cameras},
author = {Opachich, Y P and Bell, P M and Bradley, D K and Chen, N and Feng, J and Gopal, A and Hatch, B and Hilsabeck, T J and Huffman, E and Koch, J A and Landen, O L and MacPhee, A G and Nagel, S R and Udin, S},
abstractNote = {},
doi = {10.1063/1.4961302},
journal = {},
number = 11,
volume = 87,
place = {United States},
year = {Tue Oct 24 00:00:00 EDT 2017},
month = {Tue Oct 24 00:00:00 EDT 2017}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • We have designed and fabricated a structured streak camera photocathode to provide enhanced efficiency for high energy X-rays (1–12 keV). This gold coated photocathode was tested in a streak camera and compared side by side against a conventional flat thin film photocathode. Results show that the measured electron yield enhancement at energies ranging from 1 to 10 keV scales well with predictions, and that the total enhancement can be more than 3×. The spatial resolution of the streak camera does not show degradation in the structured region. We predict that the temporal resolution of the detector will also not bemore » affected as it is currently dominated by the slit width. This demonstration with Au motivates exploration of comparable enhancements with CsI and may revolutionize X-ray streak camera photocathode design.« less
  • X-ray streak cameras at Lawrence Livermore Laboratory use gold transmission photocathodes for x-ray detection. Other photocathode materials which might provide improved sensitivity without loss of temporal resolution are of interest. Of particular interest are dielectrics such as cesium iodide. Simultaneous measurements of the sensitivity to 500 eV x-rays of both gold and cesium iodide photocathodes in the LLL Soft X-ray Streak Camera were made. Enhanced sensitivity with the Csl photocathodes is reported and no degradation of temporal resolution for 100 ps x-ray pulses is seen. We have established the optimum thickness for maximum sensitivity of gold photocathodes to be 100more » A. The maximum sensitivity of cesium iodide was observed for photocathode thickness of 1100 A.« less
  • The timing fiducial system at the Nova Two-Beam Facility allows time-resolved x-ray and optical streak camera data from laser-produced plasmas to be synchronized to within 30 ps. In this system, an Al-coated optical fiber is inserted into an aperture in the cathode plate of each streak camera. The coating acts as a photocathode for a low-energy pulse of 1{omega} ({lambda} = 1.054 {mu}m) light which is synchronized to the main Nova beam. The use of the fundamental (1{omega}) for this fiducial pulse has been found to offer significant advantages over the use of the 2{omega} second harmonic ({lambda} = 0.53more » {mu}m). These advantages include brighter signals, greater reliability, and a higher relative damage threshold, allowing routine use without fiber replacement. The operation of the system is described, and experimental data and interpretations are discussed which suggest that the electron production in the Al film is due to thermionic emission. The results of detailed numerical simulations of the relevant thermal processes, undertaken to model the response of the coated fiber to 1{omega} laser pulses, are also presented, which give qualitative agreement with experimental data. Quantitative discrepancies between the modeling results and the experimental data are discussed, and suggestions for further research are given.« less
  • The performance of CsI photocathodes has been characterized for use with grazing incidence soft x rays. The total electron yield and pulsed quantum efficiency of a CsI photocathode has been measured in a reflection geometry as a function of photon energy (100 eV to 1 keV), angle of incidence, and the electric field between the anode and photocathode. The total electron yield and pulsed quantum efficiency increase as the x-ray penetration depth approaches the secondary electron escape depth. Unit quantum efficiency in a grazing incidence geometry is demonstrated. A weak electric-field dependence is observed for the total yield measurements; whilemore » no significant dependence is found for the pulsed quantum efficiency. The effect of the pulse height distribution on the detective quantum efficiency is discussed. Theoretical predictions agree accurately with experiment.« less
  • Using a soft x-ray streak camera, materials are tested for suitability as transmission photocathodes when irradiated by 0.35..mu..m laser pulses. Preliminary measurements of sensitivity, dynamic range and temporal resolution are reported. A practical fiber optic fiducial under development for laser fusion x-ray diagnostics on the LLNL Nova laser system is described.