TALIF at H⁻ ion sources for the determination of the density and EDF of atomic hydrogen

Abstract

The production of H- ions in negative ion sources relevant for particle accelerator facilities and neutral beam injection systems is based predominantly on the surface conversion of H atoms at a low work function surface covered with caesium (the plasma grid). Therefore, the H atom density n H and energy distribution function (EDF) close to the plasma grid determine the amount of surface produced H- ions. As a direct method for the density and EDF determination, two-photon absorption laser induced fluorescence (TALIF) on H atoms was implemented at the ion source of the teststand BATMAN Upgrade being the first time that this was accomplished at an H- ion source. Several challenges had to be overcome concerning the application of the diagnostic at the complex facility and the evaluation of the fluorescence signals against a bright Hα background. The observed line profiles suggest a Maxwellian EDF with an H atom temperature of (2000 ± 500) K. The presence of highly energetic H atoms (measured by optical emission spectroscopy, OES) could not be resolved by the TALIF system due to the insufficient signal-to-noise ratio. Atomic densities were measured for H2 and D2 plasmas for varying ion source parameters at BATMAN Upgrade resulting in values between 3×1018 m-3 and 1.1×1019 m-3 for hydrogen. For the operation with deuterium, 30% higher atomic densities are observed for similar ion source parameters which agree well with the previous results obtained with OES.

Concentration measurements of atomic nitrogen in an atmospheric-pressure RF plasma jet using a picosecond TALIF

“…As shown in figure 4, the slopes of the linear fits reached values 1.5 and 1.4, which shows that the saturation must be taken into account in our measurement. In the case of integrated fluorescence signal over a cylindrical symmetric laser beam cross-section, Mrkvic ˇková et al [53] presented an evaluation model for a partially saturated regime, which is also reported for dealing the saturation of H TALIF [51,54]. Accordingly, the measured TALIF signal F and laser-pulse energy E L have the following relation,…”

Design of hydrogen energy storage frequency modulation method based on primary frequency modulation of power grid

“…The general interference signal is always superimposed on the signal, changing its amplitude. So although FM waves will change in amplitude after they love to interfere, they can use a limiter at the receiving end to cut off the change in the amplitude of the signal [16][17][18][19][20] . Therefore, FM waves have excellent anti-interference performance, and FM broadcasts are received by a radio, there is almost no noise.…”

Beam divergence of RF negative hydrogen ion sources for fusion

“…Consequently, diagnostics for determining the properties of the precursor particles are presently enhanced. Consorzio RFX contributes here with the measurement of the energy distribution function of positive ions using a Retarding Field Energy Analyzer (RFEA), IPP contributes with the measurement of H properties using a Two photon Absorption Laser Induced Fluorescence (TALIF) diagnostics [23]; the investigations are on-going.…”