Monte Carlo Analysis of the Performance of the ITER Diagnostic Residual Gas Analyzer

Journal Article · Mon Aug 23 00:00:00 EDT 2021 · Fusion Science and Technology

DOI:https://doi.org/10.1080/15361055.2021.1898867· OSTI ID:1819602

Klepper, C. C.  ^[1]; Ravelli, F. A. ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

The composition of exhausted gas is a key parameter in long-pulse plasma fusion experiments, and its evolution shall be monitored at timescales relevant to plasma dynamics and plasma-wall interactions. A diagnostic residual gas analyzer (DRGA) is a multisensor instrument particularly suited to these studies, and ITER will adopt DRGAs in the equatorial and in the divertor tokamak regions. In this work, we have revisited the design of the ITER divertor DRGA through simple vacuum analytical considerations supported by simulations conducted with Molflow+, a test particle Monte Carlo (TPMC) simulation code commonly used in the particle accelerator community. Here, starting with recommendations on the manufacturing of the vacuum piping of the DRGA, this work is followed by a complete vacuum characterization of the diagnostic vacuum setup (pressure profiles at base pressure and during sampling, orifice diameter, and length optimization), and finally, the in-vessel residence time of the most important gas species is simulated. These studies have allowed us to give insights into some experimental results recently found on the prototype DRGA installed in the Wendelstein W7-X stellarator.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1819602
• Journal Information: Fusion Science and Technology, Vol. 77, Issue 7-8; ISSN 1536-1055
• Publisher: American Nuclear Society
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DRGA
ITER
W7-X
Molflow+