Single frequency scanning laser as a plasma diagnostic

Abstract

In this paper we report the development of the single frequency dye laser as a plasma diagnostic for measuring ion velocity distributions with a resolution limited only by the naturallinewidth of the laser excited resonance transition. For the 6S1!2-6P1!2 transition in Ba+ this corresponds to a velocity uncertainty of 10 3 cm/s. Velocity selection is performed by the laser as it scans the Doppler broadened plasma absorption line, in contrast with the usual method of scanning an emission line with a high-resolution spectrometer. Both sensitivity and resolution are improved by 2 orders of magnitude, allowing nonperturbing measurements to be made at densities below 10 7 cm -3. In addition to a description of the technique, sample measurements of time-resolved wave induced modifications of ion velocity distributions are shown. P ACS numbers: 52.25.Fi, 52.70.Kz

Ion acceleration and anomalous transport in the near wake of a plasma limiter

“…52 Barium is used because of the convenient electronic properties of the Ba ϩ ion, allowing the use of LIF as a diagnostic. Laser induced fluorescence techniques [53][54][55] plasma. This diagnostic is nonperturbing to the plasma, possesses good spatial, velocity, and temporal resolutions ͑1 mm 3 , 3ϫ10 3 cm/s, and 1 s, respectively͒.…”

Laser-induced fluorescence measurements for plasma processing

“…For experiments reported here, dye [3] and diode laser [28] systems were utilized for LIF work. Single species argon plasmas were produced and a metastable argon ion level was interrogated for LIF ion distributions and total signal.…”

“…Laser-induced fluorescence (LIF) developed in research laboratories beginning as early as 1975 [1][2][3]. Through scanning a single-frequency laser through a Dopplerbroadened electronic resonance, ion velocity distribution functions in the direction of the laser beam could be determined (among other plasma properties).…”

Ion heating due to modulated parametric decay

“…Ion temperatures were determined from velocity distributions measured with a laser induced fluorescence (LIF) diagnostic [18,19] which uses a tunable dye laser to induce transitions to an excited state in target plasma ions. Measuring the Doppler shifts of the decay transitions in the direction perpendicular to the magnetic field gave f(V J.…”