Spatial Profile of Neutral Temperature Measurement in Aditya-U Tokamak Plasmas

Yadava, Nandini; Ghosh, Joydeep; Chowdhuri, M. B.; Manchanda, R.; K, Sripathi Punchithaya; Dey, R.; Jadeja, K. A.; Tanna, R.L.; Tripathi, Deepti; Team, Aditya-U

doi:10.3390/atoms7030087

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“…A high-resolution space resolved spectroscopic diagnostic [22] has been developed and installed earlier on the ADITYA and later on ADITYA-U tokamak to monitor the temporal and spatial evolution of different spectral lines for estimating ion and neutral temperatures [31,32], plasma rotation [33] and studying impurity transport [25,26]. The system consists of 1 m, f /8.7 spectrometer (AM510, Acton, USA).…”

Section: Visible Spectrometers Based Diagnostic Systemsmentioning

confidence: 99%

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Physics studies of ADITYA & ADITYA-U tokamak plasmas using spectroscopic diagnostics

et al. 2022

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Several spectroscopic diagnostics encompassing the spectral emission range from the x-ray to near infrared (NIR) have been developed, installed and operated for diagnosing and physics studies in the ADITYA and ADITYA-U tokamaks. The recycling and impurity influxes and plasma Z eff after lithium (Li) coating have been studied using a PMT (photomultiplier tube)-filter based system by capturing H α , O1+, C2+, and visible continuum emissions. Significant reduction in the Z eff values has been observed in the discharge with the Li coated walls. The measured radial profile of H α emission using a filter-PMT array, has been modelled using a neutral transport code. The results show substantial contributions from the molecular hydrogen and molecular hydrogen ion dissociation (∼56%) and charge-exchange (∼30%) processes in the measured H α emission. Furthermore, a high-resolution, 1 m spectrometer with charge coupled device detector capable of multi-track measurements, has been used to study impurity transport, neutral and ion temperature and intrinsic plasma rotation. By modelling the measured radial profile of O4+ spectral line emission using an impurity transport code, substantial contribution of edge fluctuations on the oxygen transport has been observed. The toroidal ( u T max ∼ 20 km s−1 in core) and poloidal ( u θ max ∼ 4.5 km s−1 at edge) rotation velocities are measured using C5+ (529 nm) and C2+ (464.7 nm) passive line emissions respectively. The measurement of radial profile of toroidal plasma rotation revealed a reversal of rotation direction depending on the electron density content of the ADITYA-U plasmas. The neutral temperature measurements showed a poloidal asymmetry indicating a presence of asymmetrical source of neutral heating. Moreover, the modelling of measured Fe14+ and Fe15+ vacuum ultraviolet spectral lines has revealed the neo-classical nature of iron transport in ADITYA core. Fast visible camera images captured the formation of filament structures triggered by interchange instabilities during plasma disruptions.

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Section: Visible Spectrometers Based Diagnostic Systemsmentioning

confidence: 99%

“…Neutral temperature was estimated by employing fitting technique and the spatial profile of hot components of the neutral hydrogen has been plotted in figure 9. It varies within 15 to 28 eV [31]. The charge exchange process mainly produces the hot component, which comes from the plasma core.…”

Section: Poloidal Asymmetry In Neutral Temperature Of Thementioning

confidence: 99%