Research and Development of Imaging Bolometers

Abstract

An overview of the research and development of imaging bolometers giving a perspective on the applicability of this diagnostic to a fusion reactor is presented. Traditionally the total power lost from a high temperature, magnetically confined plasma through radiation and neutral particles has been measured using one dimensional arrays of resistive bolometers. The large number of signal wires associated with these resistive bolometers poses hazards not only at the vacuum interface, but also in the loss of electrical contacts that has been observed in the presence of fusion reactor levels of neutron flux. Imaging bolometers, on the other hand, use the infrared radiation from the absorbing metal foil to transfer the signal through the vacuum interface and out from behind a neutron shield. Recently a prototype imaging bolometer known as the InfraRed imaging Video Bolometer has been deployed on the JT-60U tokamak which demonstrates the ability of this diagnostic to operate in a reactor environment. The application of computed tomography demonstrates the ability of one imaging bolometer with a semi-tangential view to produce images of the plasma emissivity. In addition, new detector foil development promises to strengthen the foil and increase the sensitivity by an order of magnitude.