A new metal resistor bolometer for measuring vacuum ultraviolet and soft x radiation

Abstract

A new metal resistor bolometer has been developed by applying thin-film technology. It is composed of three layers, a 4-μm-thick radiation absorber made of gold, a 7.5-μm-thick kapton dielectric, and a 0.1-μm-thick 5-kΩ gold resistor. This detector with the appropriate electronics shows a linear response to radiation power, including both neutral-particle emission and electromagnetic radiation from the soft x-ray part of the spectrum to the infrared. The bolometer has a very high operating reliability and sufficient suppression of ambient interference under extreme environmental conditions, such as high neutron and gamma radiation fluxes, high temperatures, mechanical vibrations, and strong electromagnetic fields. In plasma discharges in the ASDEX tokamak a radiation detection limit of 100 μW/cm2 was obtained at a time resolution of 10 ms. The bolometers of an array can be calibrated in situ; the calibration data are reproducible and stable in time within ±10%. Measurements in ASDEX which demonstrate the capability of the method are discussed.