A FEASIBILITY STUDY OF A DIAGNOSTIC SYSTEM FOR JET USING LASER EXCITED LYMAN-ALPHA FLUORESCENCE TO MEASURE ATOMIC HYDROGEN DENSITIES
This study is a status report on the feasibility of Lyman-alpha lasers not a design proposal for a measuring system in a Tokamak. No suitable laser system meeting the power and linewidth requirements is yet available; frequency tripled lasers at present just allow to measure the boundary density in Tokamaks. A measuring system in a Tokamak using a frequency tripled laser is not yet in operation. A scattering system has been installed in ASDEX and first results obtained: improvements must be incorporated before reliable results can be expected from the edge of the main plasma. This report gives a detailed account of the experience gained in ASDEX with this system. Improvements should allow detection of boundary densities in the region of 10**10 particles per cm**3, at temperatures around 10 eV. For measurement of the neutral gas density profile right to the centre of the plasma the argon excimer laser with power about 2 to 3 orders of magnitude above frequency tripled lasers appeared promising. The laser was tuned to 123.2 nm, this is briefly described in this report. Experience with the argon excimer laser shows that direct intracavity tuning to Lyman alpha is not possible: we investigate tuning of the laser outside the resonator (stimulated Raman effect). The results and requirements are described in IPP-report III/89.
Bibliographic Reference: WRITE TO MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, 8046 GARCHING BEI MUENCHEN (GERMANY), MENTIONING REPORT IPP III/101, 1985
Record Number: 1989124024100 / Last updated on: 1987-01-01
Available languages: en