Entwicklung und Optimierung eines Hochtemperaturkopplungssystems Thermoanalysator Massenspektrometer

Abstract

The development of a high temperature coupling system was accomplished to carry out thermodynamic investigations during glass melting to solidify highly radioactive fission products into glass at a temperature up to 1200 °C. The actual problem consisted of the fact that the gas species evaporating from the melter have to pass without condensation or without change of their composition a multistage pressure reducing system to enter the analysator unit of the mass spectrometer in the high vacuum. With the systems, offered at present, this is only possible up to approximately 450 °C. The development of a new high temperature coupling includedinvestigations of the gas dynamics, raw materials and thermic behaviour. During the investigations the following results were accomplished: 1. The required sensitivity of detecting (substances with P$_{D} \leq$ 0.1 mb (and upwards)) is only achievable by means of nozzle-skimmer-arrangements. The skimmer is to be moved into the position directly in front of the Mach-disk at the very end of the overexpanded beam zone (of the outer nozzle). Construction permitting, the distance mass spectrometer-melting sample should be brought to a minimum. 2. The parts of the coupling system were made of a kind of chrome-nickel-steel which was resistant to high temperatures and non-corrodible up to 1180 °C; the tightenings were of platinium. An alternative installation of ceramic nozzles into the present system may be possible at any time because of the interchangeability of the elements. [...