Comparison of hollow cathode and Penning discharges for metastable He production
نویسندگان
چکیده
The production of helium 2 1S singlet metastable atoms has been investigated using a hollow cathode discharge and a Penning discharge, under dc discharge conditions. The density of metastable atoms was measured by atomic absorption using the 2 1S–3 1P transition (501.57 nm). A range of plasma currents, varying from 16 to 180 mA, and a range of pressures, from 100 mTorr to 5 Torr, were investigated. This work is directed ultimately to the production of a supersonic metastable helium beam for plasma diagnostics, in particular the measurement of electric fields using laser induced fluorescence.
منابع مشابه
Modeling the extraction of sputtered metal from high power impulse hollow cathode discharges
the extraction of sputtered metal from high power impulse hollow Abstract. High power impulse hollow cathode sputtering is studied as a means to produce high fluxes of neutral and ionized sputtered metal species. A model is constructed for the understanding and optimization of such discharges. It relates input parameters such as the geometry of the cathode, the electric pulse form and frequency...
متن کاملHollow Cathode Discharges - Analytical Applications
The low pressure glow discharges considered in this paper are the hollow cathode (Paschen), and the flat cathode (Grimm). Both discharges have similar voltage—current characteristics which are responsible for their radiation stability. The analytical sample is supplied to the discharge through a sputtering mechanism which provides a stable and non-selective source of particles. Some of the fund...
متن کاملRotationally induced Penning ionization of ultracold pho- toassociated helium dimers
– We have studied photoassociation of metastable 2S1 helium atoms near the 2 S1-2 P2asymptote by both ion detection in a magneto-optical trap and trap-loss measurements in a magnetic trap. A detailed comparison between the results of the two experiments gives insight into the mechanism of the Penning ionization process. We have identified four series of resonances corresponding to vibrational m...
متن کاملSpectral, spatial and temporal characteristics of a millisecond pulsed glow discharge: metastable argon atom production
Time resolved atomic emission, atomic absorbance, and laser-induced atomic fluorescence measurements of a Ž3 . millisecond pulsed glow discharge, made perpendicular to the insertion probe, provide temporal profiles of 1s P 5 2 Ž3 . and 1s P metastable argon atom populations. Acquisition of these profiles at different spatial positions in the 3 0 plasma provides data from which two-dimensional s...
متن کاملEffect of Collisional Disalignment on LIF Polarization Spectroscopy for Measuring Electric Field in Plasmas
We have developed a high-sensitive method for measuring the electric field in plasmas, which relies on polarization of laser-induced fluorescence (LIF) by the excitation of He atoms through forbidden transitions (e.g. 2S®4D). The aim of this work is to elucidate the effect of collisional disalignment due to He atoms and electrons in plasmas on our LIF polarization method. Hollow cathode and Pen...
متن کامل