X-ray diodes for laser fusion plasma diagnostics

Photodiodes with x-ray sensitive photocathodes are commonly used as broadband x-ray detectors in fusion plasma diagnostics. We have measured the risetime of the detector system and have measured the quantum etliciency between 1-500 A of numerous photocathode materials of practical interest. The materials studied include aluminum, copper, nickel, gold, three forms of carbon, chromium, and cesium iodideThe results of the measurements are compared with Henke’s semiempirical model of photoyield. We have studied the effects of long-term cathode aging and use as a plasma diagnostic on cathode quantum efficiency. In addition, we have measured the x-ray mass-absorption coetlicient of several ultrasoft x-ray windows in energy regions where data were unavailable. Windows studied were made of aluminum, Formvar, polypropylene, and Kimfoil. Measurements between 1-50 A were performed with the Los Alamos Scientific Laboratory’s low-energy x-ray calibration facility, and the measurements between 50550 A were performed at the National Bureau of Standard’s synchrotrons uk.raviolet radiation facility. ————————————————————

[1]  E. B. Saloman.  Typical photoefficiency between 20-250 eV of windowless XUV photodiodes with tungsten and anodized aluminum oxide photocathodes. , 1978, Applied optics.

[2]  J. Lunsford,et al.  A single-sweep 5 GHz oscilloscope-detector combination for CO2laser pulse measurements , 1977, IEEE Journal of Quantum Electronics.

[3]  Jerel A. Smith,et al.  0.1–10‐keV x‐ray‐induced electron emissions from solids—Models and secondary electron measurements , 1977 .

[4]  J. L. Gaines,et al.  X‐ray–induced electron emission from thin gold foils , 1976 .

[5]  G. Beck.  Photodiode and holder with 60 psec response time , 1976 .

[6]  C. Kunz,et al.  Optical constants from the far infrared to the x-ray region: Mg, Al, Cu, Ag, Au, Bi, C, and Al 2 O 3 , 1975 .

[7]  E. B. Saloman,et al.  Absolute Radiometric Calibration of Detectors Between 200-600A. , 1975, Applied Optics.

[8]  D. Lier,et al.  Fabrication and X-Ray Calibration of Thin Plastic Scintillator Detectors , 1975, IEEE Transactions on Nuclear Science.

[9]  Burton L. Henke,et al.  Low Energy X-Ray and Electron Absorption Within Solids (100-1500 eV Region). , 1973 .

[10]  P. B. Lyons,et al.  A total absorption ionization chamber for 1.5–10 keV X rays , 1971 .

[11]  E. Briggs,et al.  X-ray cross section compilation from 0. 1 keV to 1 MeV. Input data and supplemental results. Volume II, revision 1. Final report, 28 Apr 1970--31 Jul 1971 , 1971 .

[12]  W. H. McMaster,et al.  Compilation of x-ray cross sections UCRL-50174, sections I, II revision 1, III, IV* , 1970 .

[13]  Lellery Storm,et al.  Photon cross sections from 1 keV to 100 MeV for elements Z=1 to Z=100 , 1970 .

[14]  R. Cairns,et al.  Metal Photocathodes as Secondary Standards for Absolute Intensity Measurements in the Vacuum Ultraviolet , 1966 .

[15]  E. Burns.  Soft X-Ray Vacuum Ultraviolet Diagnostics of High Density, High Temperature Plasmas at the Air Force Weapons Laboratory , 1974 .