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  A system for cryogenic hydrogen pellet high speed inboard launch into a fusion device via guiding tube transfer

Lang, P. T., Cierpka, P., Gehre, O., Reich, M., Wittmann, C., Hobirk, J., et al. (2003). A system for cryogenic hydrogen pellet high speed inboard launch into a fusion device via guiding tube transfer. Review of Scientific Instruments, 74(9), 3974-3983. doi:10.1063/1.1602940.

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Lang, P. T.1, Author           
Cierpka, P.1, Author           
Gehre, O.1, Author           
Reich, M.1, Author           
Wittmann, C.1, Author           
Hobirk, J.1, Author           
ASDEX Upgrade Team2, Author
Lorenz, A.1, Author           
Frigione, D.3, Author
Kalvin, S.3, Author
Kocsis, G.3, Author
Maruyama, S.3, Author
1Experimental Plasma Physics 1 (E1), Max Planck Institute for Plasma Physics, Max Planck Society, ou_1856295              
2Max Planck Society, ou_persistent13              
3EFDA-CSU, Culham Science Center, Abingdon, OX14 3DB, United Kingdom; Centro Richerche Energia, ENEA, Via Enrico Fermi, 40-00044 Frascati (RM), Italy; KFKI-RMKI, EURATOM Association, P.O. Box 49, H-1525 Budapest, Hungary; ITER International Team, Garching Joint Work Site, Boltzmannstrasse 2, 85748 Garching, Germany, ou_persistent22              


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 Abstract: Particle deposition deep inside the hot target plasma column by cryogenic hydrogen pellet injection is required for efficient particle refueling of fusion devices such as tokamaks. As the ablation plasmoid is subject to a strong outward drift in hot plasmas, pellet launch from the tokamak inboard side is more useful than from the outboard. The depth of the pellet particle deposition depends on density and temperature of the target plasma, and on the pellet mass and velocity. Plasma operation determines density and temperature values, the maximum affordable density perturbation limits the pellet mass. Consequently, the pellet speed remains the only technically variable parameter allowing improvement of the refueling performance. To achieve this an inboard high-speed pellet injection system based on looping type geometry was designed and built at the midsize tokamak ASDEX Upgrade, and first fueling studies had validated the potential for the required injection velocity increase. Throughout the last two years experimental efforts focused on careful step-by-step optimization of the different system hardware components and the operational procedures. Introducing amongst other features a well pumped, rectangular guide track section, the feasibility for the inboard launch scheme up to an injection velocity of 1 km/s was successfully demonstrated. Detailed off-line tests have confirmed that pellets can withstand controlled mechanical and thermal impact even at this high speed, albeit for the sacrifice of increasing and significant mass losses. In a first application to plasma refueling deep penetration into hot target plasmas and hence, high fueling performance was achieved by deeper pellet born particle deposition and hence enhanced particle sustainment times.


Language(s): eng - English
 Dates: 2003
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Degree: -



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Title: Review of Scientific Instruments
  Alternative Title : Rev. Sci. Instrum.
Source Genre: Journal
Publ. Info: Copyright © 2003 American Institute of Physics
Pages: - Volume / Issue: 74 (9) Sequence Number: - Start / End Page: 3974 - 3983 Identifier: -