PHOTODETACHMENT DIAGNOSTICS OF PLASMA WITH A HIGH N- N(E) RATIO/

The method of determination of the electron and H- densities in the ph otodetachment experiment, particularly when performed in plasma with a high n_/n(e) ratio, is discussed. Some essential peculiarities of thi s method arise from the creation of a potential well in plasma after p hotodetachment. The well captures the excess electrons, generated by t he laser beam, and supports the quasineutrality in the plasma. The met hod is applied to the diagnostics of the extraction region of the nega tive ion source ''Camembert III.'' The dependencies of the negative io n and electron densities, and of the electron temperature upon the pla sma electrode voltage, are obtained and discussed. (C) 1996 American I nstitute of Physics.