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.

Effects of low pressure plasma irradiation on electrical resistivity of perovskite oxide Eu 1-x Sr x MnO 3

“…The spatially and temporally resolved measurements of total (broad band) radiated power loss (and also losses from neutral particles) from a high temperature plasma can be effectively made by bolometer [7]. Bolometers diagnostics can be used to measure the radiation over a wide spectrum, from the soft x-rays to the infrared, with a nearly uniform response at all wavelengths.…”

Development of imaging bolometers for magnetic fusion reactors (invited)

“…The sensitivity of the IRVB is given by the equation for noise equivalent power density ͑NEPD͒, S IRVB , 11,13 …”

“…In addition, practical considerations such as melting point and the availability of thin large foils should be evaluated. Such parameters have been considered 13 and the prime candidates for an IRVB foil are W, Ta, and Pt, whose properties are shown along with those of gold in Table I. While gold has been used previously, it is not suitable for use in a neutron rich reactor environment due to the tendency for transmutation to Hg ͑Ref.…”

Development of Infrared Imaging Video Bolometer for the ADITYA Tokamak

“…Bolometer is the important diagnostic tool to measure radiation power loss from plasma devices [1][2][3][4][5][6][7][8][9]. Standard types of bolometer used for the measurement of radiated power from plasma devices are metal foil resistive bolometers [7], AXUV diode based bolometers [8], thermopile bolometer and infrared bolometer [9].…”