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A compact high repetition rate XeCl excimer laser (CHIRP) has been developed for testbed purposes at Culham Laboratory. It features a novel gas flow circuit inside a single cylindrical pressure vessel which also encloses the discharge electrodes and centrifugal gas circulators. The average gas flow velocity in the laser cavity is 70m/s. The volume of the vessel (0.25m3) has been minimised to reduce gas costs and otherwise be compatible with industrial shop-floor operation. A Mach-Zehnder interferometer and an image converter camera have been used to visualise discharge-induced shocks and waves in single shot mode. Three sources of shocks and waves have been identified. The first is at the plasma-gas boundary, where two shocks are created, one of which travels upstream and the other downstream through the gas flow duct. The second source is the thin sheath region near the cathode (i.e. the plasma-cathode boundary),which produces a transverse shock, travelling towards the anode. The third source is the mesh anode which produces a rarefaction wave followed by a compression wave, both travelling towards the cathode. Above the detection threshold of the present interferometer system, density variations due to shocks and waves have been found in the discharge region up to 180 micro-s after the discharge.

Additional information

Authors: FIERET J, AEA Technology, Culham Laboratory, Abingdon, Oxon. (GB)
Bibliographic Reference: Report: CLM-P882 EN (1990) 10pp.
Availability: Available from the Librarian, UKAEA, Culham Laboratory, Abingdon, Oxon. OX14 3DB (GB)
Record Number: 199010992 / Last updated on: 1994-12-01
Original language: en
Available languages: en