Evaluation of the rod-pinch diode as a high-resolution source for flash radiography at 2 to 4 MV

Abstract

Summary form only given, as follows. The rod-pinch electron-beam diode as a source for high-resolution, penetrating flash radiography at voltages between 2 and 4 MV has been evaluated on the ASTERIX generator (6 to 7 MV, /spl sim/60 /spl Omega/, /spl sim/50-ns FWHM) located at the Centre d'Etudes de Gramat (CEG) in Gramat, France. This generator was modified for positive polarity operation, and a rod-pinch diode load was fielded. Diagnostics for this load include current and voltage probes to measure the diode electrical behavior, TLDs and RPLs to measure the radiation dose, pin diode and scintillator/photodiode detectors to determine the radiation time-history, two pinhole-cameras to image the radiation source, and a I-m radius tungsten rolled to measure the source diameter. Successful rod-pinch operation was achieved at 4 MV. An intense pinch and radiation emission was produced at the tip of the anode rod. Doses of up to 20 R were produced at I in from the rod-pinch tip in the forward direction. The dose/charge scales quadratically with the diode voltage from 1.5 to 4 MV. These data can also be fit by a radiographer's equation. For a 1-mm diameter tapered anode rod, the source diameter in the forward direction is 0.8 mm (FWHM of the derivative of the measured edge spread function). The source diameter scales linearly with rod diameter for rods from 0.5 to 2.0 mm in diameter. The source distribution appears to have a Bennett profile. The angular distribution of the radiation was measured with three pin diode detectors and will be discussed. Finally, results from this experiment will be compared with other rod-pinch results at lower voltage.