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Title: Sub 100 psec x-ray gating cameras for ICF Imaging applications

Abstract

In this paper we report on several of the technical advances made at LLNL in the gating of MCP x-ray detectors over the past two years, and show typical results obtained from implosions. The essential features of a gated microchannelplate (MCP) detector are discussed in this paper. A pulsed voltage (typically 1 kV, 100 psec) is applied across a MCP. The voltage is applied by gold conducting layers on the MCP, which form a microstrip line with the glass of the MCP. The voltage is applied by gold conducting layers on the MCP, which form a microstrip line with the glass of the MCP being the dielectric. While the voltage is applied the photo electrons resulting from x-ray photons incident on the coated surface of the MCP are amplified with typically 10{sup 3} gain. Because the gain is non-linear with the applied voltage, (subject to consideration on the electron transit line in the MCP, Section IV) there can be narrowing of the optical'' gate with respect to the electrical gate. This relaxes the pulse voltage requirement for the MCP, to FWHM {approximately}100 psec, and voltages of typically 1 kV into typically 25W. In Section II we discuss the novel approachmore » we use for the generation of the electrical pulses required for the gated MCP cameras. The spatial resolution and the factors affecting it are described in Section III. We discuss the temporal resolution of the MCP detectors in Section IV, and in Section V we discuss the configuration of microstrip coating on MCP detectors we have used and some typical results from laser driven implosions. Off line tests showing ultra font gating are described in Section VI.« less

Authors:
; ; ; ; ; ; ; ; ;  [1]
  1. (Rochester Univ., NY (USA). Lab. for Laser Energetics)
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (USA)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (USA)
OSTI Identifier:
5816518
Report Number(s):
UCRL-JC-106065; CONF-9009248-6
ON: DE91011202
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: 19. international congress on high speed photography and photonics, Cambridge (UK), 16-22 Sep 1990
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; LASER IMPLOSIONS; X-RAY DETECTION; CAMERAS; CHARGE-COUPLED DEVICES; ICF DEVICES; LASER TARGETS; SPATIAL RESOLUTION; DETECTION; IMPLOSIONS; RADIATION DETECTION; RESOLUTION; SEMICONDUCTOR DEVICES; TARGETS; THERMONUCLEAR DEVICES; 700208* - Fusion Power Plant Technology- Inertial Confinement Technology

Citation Formats

Kilkenny, J.D., Bell, P.M., Hammel, B.A., Hanks, R., Landen, O., McEwan, T., Montgomery, D.S., Turner, R.E., Wiedwald, J.D., and Bradley, D.K. Sub 100 psec x-ray gating cameras for ICF Imaging applications. United States: N. p., 1990. Web.
Kilkenny, J.D., Bell, P.M., Hammel, B.A., Hanks, R., Landen, O., McEwan, T., Montgomery, D.S., Turner, R.E., Wiedwald, J.D., & Bradley, D.K. Sub 100 psec x-ray gating cameras for ICF Imaging applications. United States.
Kilkenny, J.D., Bell, P.M., Hammel, B.A., Hanks, R., Landen, O., McEwan, T., Montgomery, D.S., Turner, R.E., Wiedwald, J.D., and Bradley, D.K. 1990. "Sub 100 psec x-ray gating cameras for ICF Imaging applications". United States. doi:.
@article{osti_5816518,
title = {Sub 100 psec x-ray gating cameras for ICF Imaging applications},
author = {Kilkenny, J.D. and Bell, P.M. and Hammel, B.A. and Hanks, R. and Landen, O. and McEwan, T. and Montgomery, D.S. and Turner, R.E. and Wiedwald, J.D. and Bradley, D.K.},
abstractNote = {In this paper we report on several of the technical advances made at LLNL in the gating of MCP x-ray detectors over the past two years, and show typical results obtained from implosions. The essential features of a gated microchannelplate (MCP) detector are discussed in this paper. A pulsed voltage (typically 1 kV, 100 psec) is applied across a MCP. The voltage is applied by gold conducting layers on the MCP, which form a microstrip line with the glass of the MCP. The voltage is applied by gold conducting layers on the MCP, which form a microstrip line with the glass of the MCP being the dielectric. While the voltage is applied the photo electrons resulting from x-ray photons incident on the coated surface of the MCP are amplified with typically 10{sup 3} gain. Because the gain is non-linear with the applied voltage, (subject to consideration on the electron transit line in the MCP, Section IV) there can be narrowing of the optical'' gate with respect to the electrical gate. This relaxes the pulse voltage requirement for the MCP, to FWHM {approximately}100 psec, and voltages of typically 1 kV into typically 25W. In Section II we discuss the novel approach we use for the generation of the electrical pulses required for the gated MCP cameras. The spatial resolution and the factors affecting it are described in Section III. We discuss the temporal resolution of the MCP detectors in Section IV, and in Section V we discuss the configuration of microstrip coating on MCP detectors we have used and some typical results from laser driven implosions. Off line tests showing ultra font gating are described in Section VI.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1990,
month = 8
}

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  • High speed, high x-ray energy imaging of implosions is a key diagnostic technique in the glass laser implosion program in the USA. With the correct x-ray energy, time gated images can measure the symmetry and mix of the imploding shell into the stagnated fuel if the spatial resolution of 10 or 5 [mu]m matched by a temporal resolution of 100 or 50 psec. Several 100 psec microchannelplate (MCP) x-ray pin hole cameras have been installed and run on large laser systems with improving reliability. To increase the sensitivity of the imaging system a ring aperture microscope has been coupled tomore » a gated MCP detector allowing imaging at up to 8 keV. To achieve 40 psec resolution, thinner MCP's are required. On line tests with a thin low gain, but high speed MCP, followed by a d.c. MCP for higher gain have demonstrated 40 psec gating, but the second plate may lead to an unacceptable sensitivity of the camera to hard x-rays. Off line tests have extensively investigated the properties of thinner MCP's and good agreement is seen with modeling.« less
  • High speed, high x-ray energy imaging of implosions is a key diagnostic technique in the glass laser implosion program in the USA. With the correct x-ray energy, time gated images can measure the symmetry and mix of the imploding shell into the stagnated fuel if the spatial resolution of 10 or 5 {mu}m matched by a temporal resolution of 100 or 50 psec. Several 100 psec microchannelplate (MCP) x-ray pin hole cameras have been installed and run on large laser systems with improving reliability. To increase the sensitivity of the imaging system a ring aperture microscope has been coupled tomore » a gated MCP detector allowing imaging at up to 8 keV. To achieve 40 psec resolution, thinner MCP`s are required. On line tests with a thin low gain, but high speed MCP, followed by a d.c. MCP for higher gain have demonstrated 40 psec gating, but the second plate may lead to an unacceptable sensitivity of the camera to hard x-rays. Off line tests have extensively investigated the properties of thinner MCP`s and good agreement is seen with modeling.« less
  • This invited paper focuses on high speed electronic/electro-optic camera development by the Applied Physics Experiments and Imaging Measurements Group (P-15) of Los Alamos National Laboratory`s Physics Division over the last two decades. The evolution of TV and image intensifier sensors and fast readout fast shuttered cameras are discussed. Their use in nuclear, military, and medical imaging applications are presented. Several salient characteristics and anomalies associated with single-pulse and high repetition rate performance of the cameras/sensors are included from earlier studies to emphasize their effects on radiometric accuracy of electronic framing cameras. The Group`s test and evaluation capabilities for characterization ofmore » imaging type electro-optic sensors and sensor components including Focal Plane Arrays, gated Image Intensifiers, microchannel plates, and phosphors are discussed. Two new unique facilities, the High Speed Solid State Imager Test Station (HSTS) and the Electron Gun Vacuum Test Chamber (EGTC) arc described. A summary of the Group`s current and developmental camera designs and R&D initiatives are included.« less
  • Los Alamos National Laboratory has designed and prototyped high-frame rate intensified/shuttered Charge-Coupled-Device (CCD) cameras capable of operating at kilohertz frame rates (non-interlaced mode) with optical shutters capable of acquiring nanosecond-to-microsecond exposures each frame. These cameras utilize an Interline Transfer CCD, Loral Fairchild CCD-222 with 244 {times} 380 pixels operated at pixel rates approaching 100 Mhz. Initial prototype designs demonstrated single-port serial readout rates exceeding 3.97 Kilohertz with greater than 51p/mm spatial resolution at shutter speeds as short as 5ns. Readout was achieved by using a truncated format of 128 {times} 128 pixels by partial masking of the CCD and thenmore » subclocking the array at approximately 65Mhz pixel rate. Shuttering was accomplished with a proximity focused microchannel plate (MCP) image intensifier (MCPII) that incorporated a high strip current MCP and a design modification for high-speed stripline gating geometry to provide both fast shuttering and high repetition rate capabilities. Later camera designs use a close-packed quadruple head geometry fabricated using an array of four separate CCDs (pseudo 4-port device). This design provides four video outputs with optional parallel or time-phased sequential readout modes. The quad head format was designed with flexibility for coupling to various image intensifier configurations, including individual intensifiers for each CCD imager, a single intensifier with fiber optic or lens/prism coupled fanout of the input image to be shared by the four CCD imagers or a large diameter phosphor screen of a gateable framing type intensifier for time sequential relaying of a complete new input image to each CCD imager. Camera designs and their potential use in ongoing military and medical time-resolved imaging applications are discussed.« less
  • The soft x-ray microstripline microchannel plate (MCP) framing camera has become one of the workhorses of ICF diagnostics. Much progress has been made in making these diagnostics work well with gate times of 100 ps and below. Often weak input signal or source timing uncertainties dictate a requirement for longer gate times, preferably in the same instrument that also has fast gating capability. The large power-law dependence of MCP gain on applied voltage is useful in shortening the gating time of the microstripline camera. However, this sensitivity leads to tight constraints on the shape of the long duration electrical pulsesmore » that are needed to drive the MCP to produce experimentally desirable optical gating profiles. Simple modeling and measurements are used to better understand the character of the voltage pulses needed to achieve optical gate widths between 500 ps and {approx}2 ns.« less