Regeneration of cryosorbing exhaust gas panels by means of gyrotron radiation

The exhaust gas of the planned fusion reactor ITER (R. Aymar, Fus. Eng. Des. vol. 55, pp. 107-118, 2001) consists of up to 10% helium and 90% hydrogen. The extraction of these gases from the reactor space is achieved by cryopumps comprising several cryogenically cooled flat panels having in total an absorbing surface of about 35 m/sup 2/. As can be seen in the cross section of a panel, a 4 K cooled quilted steel plate is covered with activated carbon grains, serving as the absorbing material, glued onto the metal surface. In periodic cycles the pump has to be disconnected from the vessel and rapidly heated (during 75 s) to 80-100 K to regenerate the surface. After heating, rapid cooling down to cryogenic temperatures, also in 75 s, is necessary. If the heating and cooling is performed by just changing the temperature of the coolant, the energy consumption is extremely high. Here we investigate the application of microwave radiation to heat the carbon layer exclusively.