The measurement of the optical transmission through the plasma of a laser beam, swept in frequency around the resonance absorption lines of atomic or ionic species, allows the direct acquisition of new information on the kinetics of both neutral and ionic species, separating the contributions of the different components of the plasma. The high intensity of the laser allows one to obtain a good signal-to-noise ratio in absorption spectroscopy, even in the presence of the high luminous background of the plasma. This technique has been applied to several experimental condition. We have studied the plasma parameters of an Ar laser tube discharge in a current densities range between 400 and 1200 A/cm(2). Both transitions leaving from the neutral 1s(5)(P-3(2)) metastable level (in the near IR) and from the metastable or long-lived 3p(4)(P-3)3d(4)F ionic levels were observed (in the red). Information was obtained about the temperatures, the population densities in the metastable states, and the cataphoretic speed in the discharge both for neutral and for single-ionized species. Particular care was devoted to investigate the properties of the discharge in a transverse magnetic field, which is able to enhance the laser emission power.
Diagnostic of argon discharges through diode lasers
BEVERINI, NICOLO';MACCARRONE, FRANCESCO;MARSILI, PAOLO;STRUMIA, FRANCO
1998-01-01
Abstract
The measurement of the optical transmission through the plasma of a laser beam, swept in frequency around the resonance absorption lines of atomic or ionic species, allows the direct acquisition of new information on the kinetics of both neutral and ionic species, separating the contributions of the different components of the plasma. The high intensity of the laser allows one to obtain a good signal-to-noise ratio in absorption spectroscopy, even in the presence of the high luminous background of the plasma. This technique has been applied to several experimental condition. We have studied the plasma parameters of an Ar laser tube discharge in a current densities range between 400 and 1200 A/cm(2). Both transitions leaving from the neutral 1s(5)(P-3(2)) metastable level (in the near IR) and from the metastable or long-lived 3p(4)(P-3)3d(4)F ionic levels were observed (in the red). Information was obtained about the temperatures, the population densities in the metastable states, and the cataphoretic speed in the discharge both for neutral and for single-ionized species. Particular care was devoted to investigate the properties of the discharge in a transverse magnetic field, which is able to enhance the laser emission power.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
