Design, fabrication and characterization of an x-ray bolometer for pulsed plasma x-ray sources

摘要

An x-ray bolometer for absolute measurement of broad-band soft x-ray fluence (10 eV < hv < 5 keV) from pulsed plasma sources is fabricated using an optical lithography technique. It is based on detecting the increase in resistance of a thin gold microstructure due to the temperature rise caused by absorption of x-ray energy in the absorber of the bolometer. The increase in the resistance is detected in a balanced bridge circuit and amplified by a low drift, high gain differential amplifier. The bolometer is calibrated for absolute sensitivity by comparing the signal of XUV pin diodes of known standard response detecting soft x-rays from a laser produced plasma. The response of the bolometer is measured to be approx1.12 +- 0.05 mV mJ~(-1), with a heating time constant of 0.68 ms and a cooling time constant of 6 s. These values are found to be in good agreement with those derived using a simple analogy of charging of a capacitor by a pulsed signal. The details of bolometer design, fabrication and its characterization using x-rays (hv > 0.8 keV) from a copper plasma are presented.