Outgassing. The outgassing rates of materials used on ITER vacuum systems shall be consistent with the values in Table 5-1. Appendix 17 gives details on how outgassing requirements are derived, how they can be achieved and how they may be measured. Maximum Steady State Outgassing rate Pa.m3.s-1.m-2 VQC+ Outgas temperature C Hydrogen isotopes Impurities Testing Guidelines 1 100‡ 1 x 10-7 1 x 10-9 Appendix 17 2 20 1 x 10-7* Appendix 17 For VQC 2, 3 and 4, the outgassing rate excludes the partial outgassing rates for water and hydrogen. ‡ The outgas test temperature can be reduced to 20 C for components which normally operate at cryogenic temperatures. + For CFC refer to section 26.7 * In the case of resins for magnets it is considered that this target outgassing rate will be achievable. However, a factor of 10 increase will be permitted as an acceptance criterion. These limits have been produced by taking into account the total surface area expected, the available pumping speed, the desired pressure and post assembly conditioning time, with due consideration of what is reasonably achievable. The addition of novel high surface area components to the design requires specific acceptance and appropriate limits to be assessed. Published data and/or experimental trials shall be used to show design and process consistency with the limits.
