Chapter 105 - Design and manufacturing of cryosorption pumps for testbeds of ITER relevant neutral beam injectors

Abstract

This chapter describes the design of large cryosorption pumps that are used to pump high gasloads of hydrogen and deuterium needed for neutral beam injectors (NBI). The calculations of the heatloads are pointed out, and based on the heatloads the thermo hydraulic behaviors have been examined. Special cryosorption pumps based on the adsorption with activated charcoal, coated onto cryopanels in quilted design have been developed and manufactured at Forschungszentrum Karlsruhe (FZK). The cryopanels have been integrated in the 1:2 scaled ITER torus cryopump installed at the FZK testbed TIMO (Test Facility for ITER Model Pump) to determine the pumping properties. For the international nuclear fusion project ITER the NBI system makes great demands on the pumping requirements. The gasload for the hydrogen operation of the NBI is given with 33.83Pam3/s and during deuterium operation it is about 18Pam3/s. To handle these gasloads and establish the necessary pressure profile during the operation of the beam line a pumping speed of 3800m3/s for hydrogen and 2600m3/s for deuterium is needed. The pressure profile along the beam line is realized with a diaphragm placed in the middle of the cryopump. Thus, the pressure in the second chamber should be thirty times lower than in the first chamber to avoid the reionization of the neutral gas beam.