Gain uniformity, linearity, saturation and depletion in gated microchannel-plate x-ray framing cameras
- Lawrence Livermore National Lab., CA (United States)
- Los Alamos National Lab., NM (United States)
- Univ. of Rochester, NY (United States). Lab. for Laser Energetics
The pulsed characteristics of gated, stripline configuration microchannel-plate (MCP) detectors used in X-ray framing cameras deployed on laser plasma experiments worldwide are examined in greater detail. The detectors are calibrated using short (20 ps) and long (500 ps) pulse X-ray irradiation and 3--60 ps, deep UV (202 and 213 nm), spatially-smoothed laser irradiation. Two-dimensional unsaturated gain profiles show < 5% percent long-range transverse variations but up to 3 dB/cm drop in gain parallel to the pulse propagation direction. Up to 50% gain enhancements due to voltage reflection from the bends of a meander stripline geometry and from the ends of conventional straight striplines are also observed. Reproducible gate profiles are obtained with either picosecond X-ray or UV bursts and FWHM extracted with 3 picosecond accuracy. A novel single-shot method for measuring local gate propagation speeds using a tilted MCP is also demonstrated. Detailed output versus input studies indicate a linear dynamic range of 300. At higher irradiances, the gradual transition from linear behavior to hard saturation is gathered over a range of 10{sup 5} in irradiation and fitted using a discrete dynode model. Finally, a pump-probe experiment quantifying for the first time long-suspected gain depletion by strong localized irradiation was performed. The mechanism for the extra voltage and hence gain degradation is shown to be associated with intense MCP irradiation in the presence of the voltage pulse, at a fluence at least an order of magnitude above that necessary for saturation. Results obtained for both constant pump area and constant pump fluence are presented. The data are well modeled by calculating the instantaneous electrical energy loss due to the intense charge extraction at the pump site and then recalculating the gain downstream at the probe site given the pump-dependent degradation in voltage amplitude.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 10181545
- Report Number(s):
- UCRL-JC-112384; CONF-930722-60; ON: DE94018596; TRN: 94:018940
- Resource Relation:
- Conference: Annual meeting of the Society of Photo-Optical Instrumentation Engineers (SPIE),San Diego, CA (United States),11-16 Jul 1993; Other Information: PBD: 20 Jul 1994
- Country of Publication:
- United States
- Language:
- English
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