Upgrade of Imaging Bolometers on LHD

Abstract

Infrared Imaging Video Bolometers (IRVB) provide an image of the plasma radiation by using a thin metal foil to absorb the radiation, which is then imaged by an IR camera. In LHD IRVBs at Ports 6-T and 1-O have been upgraded. Both of the ∼ 1 micron × 70 mm × 90 mm gold foils have been replaced with ∼ 2.5 micron Pt foils of the same area for greater sensitivity (Pt vs Au) and absorption of higher energy photons estimated up to 8.2 keV. Also the IR cameras have been replaced; an FLIR/SC500 (∼ 100 mK, 60 fps, 320 × 240 pixels) IR camera at Port 1-O with a FLIR/Phoenix (∼ 16 mK, 345 fps, 320 × 256 pixels) IR camera at Port 10-O and an AGEMA/THV 900 LW (∼ 190 mK, 15 fps, 136 × 272 pixels)] with a FLIR SC-4000 (∼ 19 mK, 327 fps, 320 × 256 pixels) IR camera at port 6-T. In the current campaign these IRVBs will use 8 mm × 8 mm apertures resulting in 12 × 16 channels on the foil. The noise equivalent power density for these two new IRVBs ranges from ∼ 360 µW/cm2 for 327 fps operation to 3.6 µW/cm2 for 15 fps operation, which is over two orders of magnitude of improvement over the previous IRVB at Port 6-T.