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Proceedings Paper

Photoelectron current saturation in streak tubes used for high-dynamic-range measurements on inertial confinement fusion lasers
Author(s): Alain Mens; Alain Adolf; Dominique Gontier; Catherine Goulmy; Paul A. Jaanimagi; Christian Quine; Jean-Claude Rebuffie; Jacques Segre; Roger Verrecchia
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Paper Abstract

High precision and high dynamic range measurements are required to properly characterize the pulseshape in ICF laser systems. The dynamic range and precision of the measurements that can be made with streak tubes is determined by the number of photoelectrons that can be transported to the recording screen per channel and per temporal sample of the signal. They are limited by the overall current that the tube can deliver without distorting the signal. In order to build tubes with the large dynamic ranges required by this application, we need to understand at what current density level the tube response becomes nonlinear. We present results of experiments made by using a laser illuminating several streak tubes at various intensities. We show that charge depletion in the photocathode can occur in pulsed mode and limit the signal to levels well below that where space charge induced nonlinearities appear. The use of scientific grade CCD's for recording the streak traces has allowed the introduction of a new method to measure the absolute current in the tube. A 2D PIC electron optics code has been used to simulate the propagation of the beam in the input diode (photocathode/accelerating electrode) and in the drift region (accelerating electrode/screen) of a bilamellar streak tube. We compare the numerical results with the experiments. We conclude by comparing the bilamellar and classical electron optics tubes and show the advantages of the former tube design for this application.

Paper Details

Date Published: 28 May 1997
PDF: 10 pages
Proc. SPIE 2869, 22nd International Congress on High-Speed Photography and Photonics, (28 May 1997); doi: 10.1117/12.273386
Show Author Affiliations
Alain Mens, CEA Limeil-Valenton (France)
Alain Adolf, CEA Limeil-Valenton (France)
Dominique Gontier, CEA Limeil-Valenton (France)
Catherine Goulmy, Philips Photonique (France)
Paul A. Jaanimagi, Univ. of Rochester (United States)
Christian Quine, CEA Limeil-Valenton (France)
Jean-Claude Rebuffie, Philips Photonique (France)
Jacques Segre, CEA Limeil-Valenton (France)
Roger Verrecchia, CEA Limeil-Valenton (France)

Published in SPIE Proceedings Vol. 2869:
22nd International Congress on High-Speed Photography and Photonics
Dennis L. Paisley; ALan M. Frank, Editor(s)

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