, Volume 244, Issue 1, pp 70-85

Radiation losses of a theta pinch plasma in the wave-length range 10–200 Å

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Abstract

In order to measure the radiation losses of a theta pinch plasma (electron densityn e=1−5×1016 cm−3, electron temperatureT e=150−350 eV), a grazing incidence spectrograph is absolutely calibrated in the range 10–200 Å. This is done in two steps: First the measured intensity ratios of lines emitted by hydrogen-like ions are compared with their calculated values thus yielding the relative sensitivity of the instrument. The result is confirmed by incorporating well known intensity ratios of lithium-like ions. Secondly absolute calibration is possible by hanging the spectrograph on an absolutely calibrated monochromator via the branching-ratios of lithium-like ions.

Radiation losses from the plasma turn out to be negligible as compared with heat conduction losses and the total energy radiated is found to be small compared with the energy content of the electrons, if the impurity concentration does not exceed 0.5 percent. The radiation is found to be predominantly emitted by the resonance lines of the oxygen and carbon ions O VI, O VII, O VIII, CV, CVI whereas continuum radiation and the contribution from other ions are negligible small.

However, in discharge where the oxygen concentration reaches 5 percent, radiation losses can exceed the losses by heat conduction during the early phase of the discharge. But still the final electron temperature is not significantly influenced by the impurities.

Extract of doctoral thesis submitted to Fakultät für Allgemeine Wissenschaften der Technischen Universität München, 1970.
This work was performed under the terms of the agreement on association between the Max-Planck-Institut für Plasmaphysik and EURATOM.
The author wishes to thank Prof. E. Fünfer for the opportunity of conducting these experiments in his division of the “Max-Planck-Institut für Plasmaphysik”.
He is indebted to Prof. H. Zwicker for his keen interest in the progress of the investigations.
Dr. W. Köppendörfer is thanked for many useful suggestions and discussions.
Appreciation is also due to many colleagues of Exp. Division 1 who contributed to the success of this investigation.