Speaker
Description
To overcome statistical and systematic limitations arising from the rovibrational final-state distribution of molecular tritium, future precision mass-measurement experiments are pursuing atomic tritium sources. Within the KArlsruhe Mainz Atomic Tritium Effort (KAMATE), we investigate the dissociation fraction of thermal effusive atomic sources. In these sources, molecular gas is directed through a thin tungsten capillary heated to ~2600 K, where dissociation occurs via high-temperature surface and gas-phase processes.
The dissociation efficiency is governed primarily by the gas flow rate and the temperature at the capillary exit; accurate knowledge of this exit temperature is therefore essential for quantifying the resulting atomic beam flux. However, operation under ultra-high-vacuum conditions severely limits access to the capillary, and direct-contact thermometry is impractical due to the risk of damaging the emitter or the sensor and long-term accuracy drift. Minimally invasive optical diagnostics are therefore preferred, in particular near-infrared thermal-emission spectroscopy using an InGaAs array spectrometer. Accurate temperature determination requires precise wavelength calibration, spectrometer responsivity, optical transmission characterization of the measuring setup and reliable knowledge of the tungsten surface emissivity. To reduce emissivity-driven uncertainties, a dedicated setup was developed to measure the spectral emissivity of tungsten capillaries and to track its evolution with wavelength, temperature, and repeated thermal cycling; the apparatus was subsequently built and operated at the Tritium Laboratory Karlsruhe. In this poster, we present the InGaAs-spectrometer thermometry approach and tungsten emissivity calibration, enabling robust capillary temperature measurements for dissociation and flux studies in KAMATE sources.