The Doppler Shift Spectroscopy (DSS) diagnostic is in the conceptual stage to estimate beam divergence, stripping losses, and beam uniformity of the 100 keV hydrogen Diagnostics Neutral Beam of International Thermonuclear Experimental Reactor. This DSS diagnostic is used to measure the above-mentioned parameters with an error of less than 10%. To aid the design calculations and to establish a methodology for estimation of the beam divergence, DSS measurements were carried out on the existing prototype ion source RF Operated Beam Source in India for Negative ion Research. Emissions of the fast-excited neutrals that are generated from the extracted negative ions were collected in the target tank, and the line broadening of these emissions were used for estimating beam divergence. The observed broadening is a convolution of broadenings due to beam divergence, collection optics, voltage ripple, beam focusing, and instrumental broadening. Hence, for estimating the beam divergence from the observed line broadening, a systematic line profile analysis was performed. To minimize the error in the divergence measurements, a study on error propagation in the beam divergence measurements was carried out and the error was estimated. The measurements of beam divergence were done at a constant RF power of 50 kW and a source pressure of 0.6 Pa by varying the extraction voltage from 4 kV to10 kV and the acceleration voltage from 10 kV to 15 kV. These measurements were then compared with the calorimetric divergence, and the results seemed to agree within 10%. A minimum beam divergence of ∼3° was obtained when the source was operated at an extraction voltage of ∼5 kV and at a ∼10 kV acceleration voltage, i.e., at a total applied voltage of 15 kV. This is in agreement with the values reported in experiments carried out on similar sources elsewhere.

HELicon Experiment for Negative ion source (HELEN-I) with single driver is developed with a focus on the production of negative hydrogen ions. In the Helicon wave heated plasmas, very high plasma densities (~10 !" !! ) can be attained with electron temperatures as low as ~ 1 eV in the downstream region. These conditions favor the production of negative hydrogen ions. In HELEN-I device at IPR, helicon plasma is produced using Hydrogen gas in a diverging magnetic field, created by a permanent ring magnet. RF Power (P RF ) of 800-1000W at 13.56 MHz frequency is applied to a Nagoya-III antenna to excite m = 1 helicon mode in the plasma. The plasma is confined by a multi-cusp field configuration in the expansion chamber. The transition from inductively coupled mode to Helicon mode is observed near P RF ~ 700W with plasma density ~ 10 18 m -3 and electron temperature ~ 5 eV in the driver and ~ 1eV in the expansion volume. Line integrated negative hydrogen ion density is measured in the expansion chamber by employing an Optical Emission Spectroscopy (OES) diagnostic technique using ! / ! ratio and Laser photo-detachment based Cavity Ring Down spectroscopic (CRDS) diagnostic technique. The measured value of negative hydrogen ion density is in the order of 10 16 m -3 at 6 mTorr pressure and does not vary significantly with power in the helicon mode, pressure and downstream axial magnetic field variation. The negative ion density measurements are compared with theoretically estimated values calculated using particle balance method considering different reaction rates responsible for negative hydrogen ion creation and destruction. It is to be noted that at present Caesium (Cs) is not injected in the plasma discharge to enhance ! ion density.In surface process, H-ion are produced on a low work-function surface due to surface conversion of energetic H atoms (H 0 * ) or hydrogen ions (H n + ) in the plasma [9];

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