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Fundamentals of Plasma Polishing
Published in V. K. Jain, Advanced Machining Science, 2023
Hari Narayan Singh Yadav, Manjesh Kumar, Manas Das
A schematic of a plasma polishing machine is displayed in Figure 8.5. A high vacuum discharge chamber made up of Zerodur (a lithium-aluminosilicate glass-ceramic)/sital (a crystalline glass-ceramic) material with external and internal diameters of 55.5 mm and 51 mm, respectively, are used. The setup consists of three process gas cylinders (He/Ar, SF6, and O2), and a mass flow meter which is used to control the flow rate of gases. A matching box is used to perform impedance matching between the RF generator and the discharge chamber. A vacuum pump system is used to create a vacuum inside the chamber and also to remove the exhaust gas from the vacuum chamber.
Crafting the Surface with Glow Discharge Plasmas
Published in Ken N. Strafford, Roger St. C. Smart, Ian Sare, Chinnia Subramanian, Surface Engineering, 2018
P. A. Dearnley, T. Bell, F. Hombeck
Vacuum chambers can be manufactured in a number of configurations including “horizontal,” “pit,” “bell,” and “combination” units. Specific chamber dimensions are determined by the workpiece dimensions and the production loading requirements. Modern chambers have a broad range of capability, depending upon the needs of the customer. This might range from a few kilograms in one case to loads of 30 tonnes in another. Flexibility is also important. One user of Klockner equipment needs to nitride 70,000, 1-mm diameter balls (for ballpoint pens) during one cycle. At other times, the unit can be reconfigured to nitride a 26-tonne trunnion bearing (for an eccentric press).
Thermostructural Analysis of Large Cryopumping Test Facility
Published in Fusion Science and Technology, 2023
Hemang S. Agravat, Samiran S. Mukherjee, Vishal Gupta, Paresh Panchal, Pratik Nayak, Jyoti Shankar Mishra, Ranjana Gangradey
Applications like space research, nuclear fusion, accelerators, etc., have large-size vacuum chambers that require a high vacuum (HV) to ultra-high vacuum (UHV) to carry out specific scientific investigations and research. The need for large vacuum chambers has increased over time with the progression of fusion, space, and accelerator research activities around the world. Large vacuum vessels with a HV inside are repeatedly used to conduct performance tests of various space components. Many experimental facilities, named thermal vacuum tests (Ref. 1), are available in the Indian Space Research Organization (ISRO), India. To efficiently evacuate these large chambers to a vacuum lower than 1.0E-05 mbar with large volumes, like the 1400-m3 systems such as the ITER (Ref. 2) 22 653 m3 Space Power Facility3 space simulation chamber (Space Applications Centre, ISRO), cryopumps are the solution. In such systems, large gas loads comprised of air, hydrogen, helium, and water vapor can be pumped during operations. Commercial cryopumps, such as the Gifford-McMahon (GM) cryocooler-based closed-loop refrigeration system, are widely used for many experimental and industrial purposes, whereas for large cryopumping requirements, liquid-cryogen-based cryopumps are required, such as for ITER (Ref. 4).
Pulsed vacuum drying (PVD) of wolfberry: Drying kinetics and quality attributes
Published in Drying Technology, 2018
Long Xie, Zhi-An Zheng, A. S. Mujumdar, Xiao-Ming Fang, Jun Wang, Qian Zhang, Qin Ma, Hong-Wei Xiao, Yan-Hong Liu, Zhen-Jiang Gao
Figure 2 shows a schematic diagram of the pressure regulatory drying system with a typical pressure profile in the drying chamber. The PVD equipment consists of three main parts: (a) the vacuum system which consists of a vacuum chamber (9) and a vacuum pump (1); (b) the heating system that composed of a heating water tank (4) and a heating panel (14); (c) an electronic control system (2) that regulates the vacuum chamber pressure and temperature automatically according to the real time data. The minimum pressure level that the system is capable of producing is 3.3 kPa or 0.033 bar and the time taken for the system to reach this minimum pressure from atmospheric pressure is approximately 50 s.
Final Design of the Material Plasma Exposure eXperiment
Published in Fusion Science and Technology, 2023
J. Rapp, A. Lumsdaine, A. Aaron, T. M. Biewer, T. S. Bigelow, T. Boyd, J. B. O. Caughman, D. Curry, R. C. Duckworth, R. H. Goulding, A. Hussain, M. Kaufman, C. H. Lau
The vacuum system consists of the vacuum vessel and all auxiliary systems related to providing vacuum in the MPEX, as well as the gas introduction systems (see Figs. 7 and 8). The vacuum vessel provides (1) the vacuum boundary of the plasma vacuum, (2) a contamination confinement barrier for seeded and chemically produced gases as well as hazardous materials, and (3) structural support for the in-vessel components. The vacuum chamber is actively cooled to cope with excess heat from the plasma and nonabsorbed microwaves and RF power during steady-state operation. The vacuum chamber will allow access for plasma heating, fueling, diagnostics, and in-vessel component services.