Argon ion laser-induced fluorescence with diode lasers

Abstract

Diode lasers have been used for ion temperature measurements in ArII plasmas by finding new laser-induced fluorescence ͑LIF͒ schemes suited to the present range of available wavelengths. The new LIF schemes require excitation at 664, 669, and 689 nm, all near industry-standard wavelengths. Conventional LIF measurements performed by dye lasers in ArII use 611.66 nm in vacuum, shorter than any commercially available red diode laser line, and depend on the population of the 3dЈ 2 G 9/2 metastable state. The metastable state density of the conventional LIF scheme was found to be larger than the populations of the other metastable states by an order of magnitude or less. A master oscillator power amplifier diode laser was used both in a Littman-Metcalf cavity and as an optical amplifier for a low power diode laser which was in a Littman-Metcalf cavity. Both systems provided intensity of up to 500 mW, continuously tunable over 10 nm centered at 666 nm, and were used to obtain high resolution ion velocity distribution functions.

Ion acceleration in plasmas emerging from a helicon-heated magnetic-mirror device

“…21 To measure velocity distributions by LIF, the laser frequency is tuned over a range corresponding to the Doppler-shifted line resonance of ions or atoms moving with velocity v. A novel, inexpensive, low-power (10 mW), tunable, solid-state diode-laser system is used. 22 …”

Sheared Zonal Flow ExB Drifts Predicted from Emissive Probes and Measured by Laser‐Induced Fluorescence

“…Plasma density also may be measured with lower hybrid waves. LIF is used for ion characterization [16]. Emissive probes were used for plasma potential measurements.…”

Laser-induced fluorescence ion diagnostics in light of plasma processing

“…The ion distribution from the hollow cathode was similar to that from a filament source studied in [4], hence their interchangeability for many uses is understood.…”

“…LIF with diode lasers [4] can characterize the ion beam [5] and the beam source plasma. In addition, background neutrals through which the beam propagates may be ionized, causing a low temperature non-beam plasma [6].…”