DETERMINATION OF MAGNETIC FIELD DIRECTION IN TOKAMAKS FROM LASER INDUCED LYMAN-ALPHA FLUORESCENCE IN ONE PHOTON EXCITATION
Resonant laser scattering in the Lyman-alpha line of hydrogen is investigated as a possible tool for measuring the magnetic field direction in tokamak plasmas. The method is based on the depolarisation- dependence of the scattering process. Limitations arising from depolarising collisions are studied in detail by employing a previously developed theory for the collisional redistribution of light. An error analysis is performed to derive the expected experimental precision under various plasma conditions and for laser energies ranging between 1 muJ and 10 mJ. This analysis also includes the measurement of neutral hydrogen densities. It is shown that with presently available laser powers application of the method would be restricted to the border regions of the plasma. Application to the central regions would require further developments in laser technology, especially with regard to higher powers at the wavelength of Lyman-alpha and (or) to fast repetition rates.
Bibliographic Reference: REPORT EUR-CEA-FC-1342-EN-88, AVAILABILITY: CEA/CEN, CADARACHE, F
Availability: Can be ordered online
Record Number: 1989126095800 / Last updated on: 1989-05-01
Available languages: en