Fuel particle and impurity influxes have been investigated for ADITYA-U tokamak plasma operated with toroidal belt limiter using PMT based spectroscopic diagnostic system installed on machine. The influxes of hydrogen and impurity ions are estimated using various lines of sight (LoS) terminating on the graphite limiter and stainless steel wall to understand their contributions in recycled particle and impurities into the main plasma. It is found that the influxes of neutral hydrogen and oxygen are around 4 times higher in case of LoS terminating on the limiter than the wall while carbon influxes from the both LoSs are comparable. The comparable integrated particle influxes from both LoSs indicate the important role of the wall in the recycling and presence of the impurities in the plasma. The particle confinement time (tau(p)) and recycling coefficient (R) are also estimated to quantify those from the estimated particle influxes. The tau(p) values vary between 8 to 25 ms when plasma electron density is in the range of 2.0 - 3.2 x 10(19) m(-3). Analysis of recycling coefficient, R suggests that the Plasma Facing Component (PFC) acts as the particle sink at the beginning of the plasma operational campaign. The R values tend to become more than one as the campaign progresses suggesting that the PFC acting as the particle source. (C) 2021 The Japan Society of Plasma Science and Nuclear Fusion Research

The neutral particle temperature in the edge region of the Aditya-U tokamak has been measured by recording the hydrogen Balmer alpha emission spectra at 656.28 nm from different lines of sight in both the high and low field sides. The spatial profile of the Hα emission has been recorded using a 1 m multi-track spectrometer. The neutral temperature is estimated from the Doppler broadening of the measured Hα spectrum by appropriately removing the contribution from the Zeeman splitting of the spectral lines. A computer simulation code was developed to estimate the neutral temperature by including the broadening mechanisms such as Doppler broadening and the Zeeman effect to simulate the Hα emission spectrum along with the proper convolution of the instrumental width of the diagnostic system. It has been observed that the high field side neutral temperature (~4–6 eV) during plasma flat top is almost twice that of the low field side (~2–3 eV) suggesting poloidal asymmetry in the neutral temperature.

The spatial profile of neutral hydrogen temperatures in Aditya-U tokamak plasma has been estimated from the spatial profile of the Hα spectral emissions measured using a high-resolution multi-track spectrometer, having a spectral resolution of 0.023 nm at a 50 μm entrance slit width. The neutral temperature estimation from the Doppler broadened spectral line was carried out after considering the Zeeman effect due to the magnetic field present in the tokamak. To accurately obtain the temperature of the neutral hydrogen, two temperature components (warm and hot) were required to be considered. A code was developed to obtain the neutral temperature and is used to analyze two typical plasma discharges. The temperature of warm components varies between 3 and 5 eV, while hot atoms have temperatures in the range of 15–30 eV. It was observed that the chord-integrated neutral temperature increases slightly towards the plasma core region compared to the plasma edge of Aditya-U tokamak.

The ^232Th( n,2n)^231Th reaction cross sections were measured at the neutron energies of 10.49 ± 0.29, 14.46 ± 0.26, 18.36 ± 0.24 MeV and 15.03 ± 0.003 MeV. For the first three energies, ^7Li( p,n) reaction as a neutron source at the BARC-TIFR Pelletron accelerator facility was used. For the latter energy, ^3H( d,n) neutron source using the PURNIMA neutron generator facility was used. The experiments were carried out using the activation method and off-line -ray spectrometric technique. Covariance information of various attributes of cross section was propagated to obtain the covariance matrix for the reaction cross sections. The experimental resuts obtained with reference to the two different neutron sources are then compared with the values of evaluated nuclear data files such as ENDF/B-VIII.0, JENDL 4.0, JEFF-3.2, ROSFOND-2010, TENDL-2017 and the theoretical values from TALYS-1.9 code.

The $$ ^{232} {\text{Th}}\left( {{\text{n}},2{\text{n}}} \right)^{231} {\text{Th}} $$ reaction cross sections were measured at the neutron energies of 10.49 ± 0.29, 14.46 ± 0.26, 18.36 ± 0.24 MeV and 15.03 ± 0.003 MeV. For the first three energies, $$ ^{7} {\text{Li}}\left( {{\text{p}},{\text{n}}} \right) $$ reaction as a neutron source at the BARC-TIFR Pelletron accelerator facility was used. For the latter energy, $$ ^{3} {\text{H}}\left( {{\text{d}},{\text{n}}} \right) $$ neutron source using the PURNIMA neutron generator facility was used. The experiments were carried out using the activation method and off-line $$ \upgamma $$ -ray spectrometric technique. Covariance information of various attributes of cross section was propagated to obtain the covariance matrix for the reaction cross sections. The experimental resuts obtained with reference to the two different neutron sources are then compared with the values of evaluated nuclear data files such as ENDF/B-VIII.0, JENDL 4.0, JEFF-3.2, ROSFOND-2010, TENDL-2017 and the theoretical values from TALYS-1.9 code.

The \({}_{ }^{ 2 3 2} {\text{Th(n, 2n)}}{}_{ }^{ 2 3 1} {\text{Th}}\) reaction cross sections relative to the \({}_{ }^{ 2 3 2} {\text{Th}}\)(n, f)97Zr monitor reaction at the effective neutron energies of 8.97 and 16.52 MeV have been measured by using the activation and off-line \(\gamma\)-ray spectrometry. The neutron beams were generated from the \({}_{ }^{7} {\text{Li}}\left( {{\text{p}}, {\text{n}}} \right){}_{ }^{7} {\text{Be}}\) reaction by using the proton beam energies of 11 and 18.8 MeV. Correction factors for the low energy neutrons were taken care by considering the thickness of sample and non mono-energetic neutrons. The covariance analysis in the uncertainty of the reaction cross section was carried out by using error propagation and micro-correlation technique. The present data were compared with the literature data, evaluated data and theoretical values based on TALYS-1.8 code.