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Your search keyword '"Moser, L."' showing total 2 results
Start Over Author "Moser, L." Publisher american institute of physics
2 results on '"Moser, L."'

1. Langmuir probe measurements in a magnetized capacitive discharge around a tilted RF electrode.

Author

Cherukulappurath, A., Faudot, E., Brochard, F., Heuraux, S., Hiret, P., Marot, L., Soni, K., and Moser, L.

Subjects
*LANGMUIR probes, *HEAT flux measurement, *ELECTRODES, *HOT carriers, *CURRENT-voltage curves
Abstract

Applications of magnetized Radio Frequency (RF) capacitive discharges for mirror cleaning applications of optical diagnostic systems in fusion devices and heat flux measurements have received a large interest in last years. Ensuring the ho-mogeneity of heat flux to the RF electrode requires localized measurements of plasma parameters in front of the RF electrode. Langmuir probe measurements were taken in the ALINE plasma device around the active RF electrode with the help of a 3D manipulator equipped with RF compensation. Highly negative floating potential values were recorded inside the magnetic flux tube connected to the active RF electrode whilst plasma potential remained positive. Since the difference between the plasma po-tential and the floating potential is proportional to the average electron temperature, experimental investigations were carried out in capacitive coupling and direct coupling to study the change in floating potential as a function of input gas pressure, magnetic field strength (B), and the angle between the RF electrode and magnetic field. The observed change in floating potential is attributed to the stochastic heating leading to the generation of hot electrons, which was confirmed using the Langmuir probe current-voltage curves. The experimental results are found to agree with the analytical model based on the flux balance equations. [ABSTRACT FROM AUTHOR]

Published
2023
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2. Cleaning of first mirrors in ITER by means of radio frequency discharges.

Author

Leipold, F., Reichle, R., Vorpahl, C., Mukhin, E. E., Dmitriev, A. M., Razdobarin, A. G., Samsonov, D. S., Marot, L., Moser, L., Steiner, R., and Meyer, E.

Subjects
*RADIO frequency, *RADIOMETRY, *RADIO waves, *INFRARED radiometry
Abstract

First mirrors of optical diagnostics in ITER are subject to charge exchange fluxes of Be, W, and potentially other elements. This may degrade the optical performance significantly via erosion or deposition. In order to restore reflectivity, cleaning by applying radio frequency (RF) power to the mirror itself and thus creating a discharge in front of the mirror will be used. The plasma generated in front of the mirror surface sputters off deposition, restoring its reflectivity. Although the functionality of such a mirror cleaning technique is proven in laboratory experiments, the technical implementation in ITER revealed obstacles which needs to be overcome: Since the discharge as an RF load in general is not very well matched to the power generator and transmission line, power reflections will occur leading to a thermal load of the cable. Its implementation for ITER requires additional R&D. This includes the design of mirrors as RF electrodes, as well as feeders and matching networks inside the vacuum vessel. Mitigation solutions will be evaluated and discussed. Furthermore, technical obstacles (i.e., cooling water pipes for the mirrors) need to be solved. Since cooling water lines are usually on ground potential at the feed through of the vacuum vessel, a solution to decouple the ground potential from the mirror would be a major simplification. Such a solution will be presented. [ABSTRACT FROM AUTHOR]

Published
2016
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