Bolometry

Initial Results of the bolometer array mesurements in Aditya

A considerable fraction of the input heating power of a tokamak plasma is lost through impurity line radiation mainly in the VUV to so ft X-ray spectral range. Bolometer systems installed in the tokamak are used to determine the local radiation emissivity and the total radiated power of the plasma.

Figure 1.1.2.6. (a) Signals from bolometer array on ADITYA. The number on the right corne r indicates the impact parameter (z) of each viewing cord. (b) Radiation power (W/m2) received at the detectors with chords at various impact parameters.

A new array consisting of 16 AXUV photodiodes has been recently installed on the radial port in ADITYA for bolometric measurements. The detectors have a fairly constant responsivity (0.2 -0.27 A/W) in the wavelength range, 2Å -2000Å and have a fast time response (0.5μs). The array views whole poloidal cross - section and the SOL plasma. Figure1.1.2.6. (a) sho ws the results of the various channels from a typical discharge in ADITYA. The line -integrated emissivity for the channels is shown in figure (b). We observe that the maximum line -integrated signal comes from the plasma core. Efforts are being made to dete rmine the emissivity profile.