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2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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Fusion Science and Technology
Latest News
NRC nominee Nieh commits to independent safety mission
During a Senate Environment and Public Works Committee hearing today, Ho Nieh, President Donald Trump’s nominee to serve as a commissioner at the Nuclear Regulatory Commission, was urged to maintain the agency’s independence regardless of political pressure from the Trump administration.
Muhammad Abdullah, Ahmad Ali, Riaz Khan, Osama Abdur Rehman, Zia-ur- Rehman, Shahab Ud-Din Khan, Sehrish Shakir, Shahzaib Zahid, Muhammad Ismail, Rafaqat Ali, Sarfraz Ahmad, Shahid Hussain
Fusion Science and Technology | Volume 80 | Number 6 | August 2024 | Pages 731-740
Research Article | doi.org/10.1080/15361055.2023.2241004
Articles are hosted by Taylor and Francis Online.
The MT-II is a small spherical tokamak that is currently under construction at the Pakistan Tokamak Plasma Research Institute. Wall conditioning of the MT-II vacuum vessel (VV) is an essential step to achieve a good quality vacuum for plasma experiments. This study presents an overview of the wall-conditioning techniques implemented on the MT-II VV, including baking and glow discharge cleaning (GDC). Prior to wall conditioning, the system is checked via a helium leak test machine and residual gas analyzer (RGA) to identify and remove leaks. The VV walls are baked at ~180 °C to get rapid desorption of water vapors and other impurities. After the baking process, the partial pressure of most of the carbon- and oxygen-containing impurities is reduced. In particular, the partial pressure of water vapors is reduced by 93%. Consequently, the total leak and outgassing rate is significantly reduced. To further improve the vacuum condition in the vessel, hydrogen GDC is carried out. The fill hydrogen pressure and anode voltage are optimized to get a stable glow discharge. The RGA scan shows that GDC reduces the partial pressure of H2O, O2, and CO2 by 57%, 63%, and 51%, respectively. The results signify that baking and GDC are effective techniques for wall conditioning of the MT-II VV.