Eddy Current and Gap Voltage at Electrical Contacts of ITER Diagnostic First Walls and Shield Modules during Plasma Disruptions
Authors: Yuhu Zhai, et. al.
Abstract:
ITER diagnostic port plugs perform many
functions including structural support of diagnostic systems
under high electromagnetic loads while allowing for diagnostic
access to the plasma. During plasma disruptions, a large amount
of induced current flows locally at electrical contacts between
diagnostic first walls (DFWs) and the diagnostic shield modules
(DSMs). Even a small gap voltage (10-30V) between DFWs,
DSMs and supporting rails may trigger local arcing and cause
arc damage to the conducting structure. This is particularly true
when we consider the ionized gas environment and halo current
effect. We perform global electromagnetic analysis with contact
details for DFWs and DSMs to quantify the gap voltage and local
current transfer effect during plasma disruptions. Electrical
contacts between the DFWs and DSMs may also have significant
impact on disruption load and thus affect design of the DFW
attachment scheme. Large current transfer (>100 kA) between
DFWs and DSMs through the attachment keys and tabs during
disruption implies local heating and potential welding. This
paper reviews the contact current and electrical potential
difference between the DFWs, DSMs and the port plug structure.
We also assess the impact on the system design itself due to
electrical contact among various components.
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Submitted to: 20th Topical Conference on Radio Frequency Power in Plasmas, Sorrento, Italy, June 25-28, 2013)
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Download PPPL-4914 (pdf 3.01 MB 6 pp)
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