Dose-rate field of the HERMES III flash X-ray source

Measurements show that the HERMES III flash X-ray source produces a peak dose-rate radiation field of (5+or-0.5)*10/sup 12/ rad(Si)/s over a useful area of 1000 cm/sup 2/, with a pulse width of approximately 20 ns. The primary goals of HERMES III were to produce a radiation pulse with an FWHM (full width, half maximum) of approximately 20 ns, a peak dose rate of 5*10/sup 12/ rad(Si)/s, and a dose-rate variation of less than a factor of two over a 500-cm/sup 2/ area. The secondary goals were to keep the dose-rate variation less than a factor of four over the volume defined by extending the 500-cm/sup 2/ area downstream by 15 cm and to maintain a minimum dose rate over this volume in excess of 2.5*10/sup 12/ rad(Si)/s. The dose and dose-rate pulse were measured in the hostile near-field region, where dose rates exceed 10/sup 12/ rad(Si)/s, and in the far-field region, when the diode is operated with a 53-cm anode-cathode gap. Specifically, it is shown that operation with a 53-cm gap permits both the primary and secondary goals to be achieved. The model predictions of radiation-pulse shape and width in the intense near-field and far-field regions are in excellent agreement with the measurements.<
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