A simple Peltier cold trap aperture for protection of vacuum UV optics against hydrocarbons and reliable calibration of VUV spectrometers using D2 lamps

Fiebrandt, M. and Awakowicz, P.

Volume: 31 Pages:
DOI: 10.1088/1361-6501/ab7f7a
Published: 2020

A simple Peltier cooled cold trap aperture is presented to minimize the flux of hydrocarbons on optics in vacuum UV systems. The system can be cooled down to -40 °C under vacuum. To test the effect of the cold trap, the aperture is placed in front of a high-intensity D2 lamp used for calibration in the range of 116 nm to 300 nm which is flanged to a VUV spectrometer. The influence of the aperture temperature is monitored by measuring the intensity loss rate of the Lyman-alpha emission line at 121.6 nm due to the formation of carbon contamination on the MgF2 window of the lamp depending on the Peltier temperature. The application of the aperture significantly reduced the intensity loss from approx. 20% h-1 to less than 2% h-1 and enables the reliable use of a D2 lamp for the relative intensity calibration of the spectrometer. © 2020 IOP Publishing Ltd.

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