Overview of operation and experiments in the ADITYA-U tokamak

Abstract

First indigenously built tokamak ADITYA, operated over 2 decades with circular poloidal limiter has been upgraded to a tokamak named ADITYA Upgrade for the purpose having shape plasma operation with open divertor geometry. Experiment research in ADITYA-U has made significant progress, since last FEC 2016. After installation of PFC and standard tokamak diagnostics, the Phase-I plasma operations were conducted from December 2016 with graphite toroidal belt limiter. Purely Ohmic discharges in circular plasmas supported by Filament pre-ionization was obtained. The plasma parameters, Ip ~ 80-95 kA, duration ~ 80-180 ms with toroidal field (max.) ~ 1T and chord-averaged electron density ~ 2.5 x 10^19 m^-3 has been achieved. Being a medium sized tokamak, runaway electron (RE) generation, transport and mitigation experiments have always been one of the prime focus of ADITYA-U. MHD activities and density enhancement with H2 gas puffing studied. The Phase-I operation was completed in March 2017. The Phase-II operation preparation in ADITYA-U includes calibration of magnetic diagnostics followed by commissioning of major diagnostics and installation of baking system. After repeated cycles of baking the vacuum vessel up to ~ 130°C, the Phase-II operations resumed from February 2018 and are continuing to achieve plasma parameters close to the design parameters of circular limiter plasmas using real time plasma position control. Hydrogen gas breakdown was observed in more than ~2000 discharge including Phase-I and Phase-II operation without a single failure. Several experiments, including the primary RE control with lower E/P operation and secondary RE control with fuelling of Supersonic Molecular Beam Injection as well as sonic H2 gas puffing during current flat-top and Neon gas puffing for better plasma confinement are undergoing. The dismantling of ADITYA and reassembling of ADITYA-U along with experimental results of Phase-I and Phase-II operations from ADITYA-U will be discussed.

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

“…It shows a major mismatch at the wings of the experimental Hα data. This is a direct indication that Hα does not come from the neutral particle having a single energy distribution, but should be noted here that a single Hα line may also have more than two components, as found in an LHD by Iwamae et al [23]. However, in our case, consideration of two components was sufficient to fit the experimental spectrum.…”

“…Then, the experimental spectrum was fitted with two components: the warm and hot temperatures of the neutral particles. It should be noted here that a single H α line may also have more than two components, as found in an LHD by Iwamae et al [23]. However, in our case, consideration of two components was sufficient to fit the experimental spectrum.…”

“…Aditya-U tokamak [23], an upgraded version of Aditya tokamak, has a toroidal belt limiter made of graphite on the inboard side of the wall. It also has two poloidal ring limiters that are toroidally separated at the outboard side.…”

A review of supersonic molecular beam injection for plasma fueling and physical studies in magnetic fusion devices

“…Because SMBI has a higher fueling efficiency than GP under different regimes, it could assume the role of GP in fusion devices. Because of its good performance and further optimization in the future (Yao et al 2004(Yao et al , 2007Pegourie et al 2003;Zheng et al 2013;Lang et al 2005;Soukhanovskii et al 2004;Takenaga et al 2009;Kim et al 2013;Murakami et al 2012;Mizuuchi et al 2010;Xiao et al 2014aXiao et al , 2021Yao and Baldzuhn 1933;Tanna et al 2019;Islam et al 2016), SMBI might play a pivotal Fig. 11 Fueling efficiencies of the SMBI system and GP in different plasma discharge regimes (Yuan et al 2018) role under a variety of conditions for future fusion devices, such as the start-up phase and pellet-free injection of helium discharge.…”

“…Its high fueling efficiency was also demonstrated in several tokamaks, such as HL-2A (Yao et al 2007, Tore Supra (Pegourie et al 2003), and EAST (Zheng et al 2013). Thus, it has been widely implemented in many notable fusion research devices, such as ASDEX Upgrade (Lang et al 2005), NSTX (Soukhanovskii et al 2004), JT-60U (Takenaga et al 2009) KSTAR (Kim et al 2013), LHD (Murakami et al 2012), Heliotron J (Mizuuchi et al 2010), J-TEXT (Xiao et al 2014a), W7-AS (Yao and Baldzuhn 1933), ADITYA-U (Tanna et al 2019), andGAMMA 10 (Islam et al 2016). Owing to its flexibility and fast response, the SMBI technique has also been well developed for density feedback control on HL-2A and EAST (Zheng et al 2013).…”