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Autore principale: Strauss, H. R.
Natura: Preprint
Pubblicazione: 2024
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Accesso online:https://arxiv.org/abs/2411.13256
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author Strauss, H. R.
author_facet Strauss, H. R.
contents Resistive wall tearing modes (RWTM) can cause major disruptions. A signature of RWTMs is that the rational surface is sufficiently close to the wall. For $(m,n) = (2,1)$ modes, at normalized minor radius $ρ= 0.75$, the value of $q$ is $q_{75} < 2.$ This is confirmed in simulations and theory and in a DIII-D locked mode disruption database. The $q_{75} < 2$ criterion is valid at high $β$ as well as at low $β.$ A very important feature of RWTMs is that they produce major disruptions only when the $q_{75} < 2$ criterion is satisfied. If it is not satisfied, or if the wall is ideally conducting, then the mode does not produce a major disruption, although it can produce a minor disruption. Feedback, or rotation of the mode at the wall by complex feedback, can emulate an ideal wall, preventing major disruptions. The $q_{75}$ criterion is analyzed in a linear simulations, and a simple geometric model is given.
format Preprint
id arxiv_https___arxiv_org_abs_2411_13256
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Prevention of resistive wall tearing mode major disruptions with feedback
Strauss, H. R.
Plasma Physics
Resistive wall tearing modes (RWTM) can cause major disruptions. A signature of RWTMs is that the rational surface is sufficiently close to the wall. For $(m,n) = (2,1)$ modes, at normalized minor radius $ρ= 0.75$, the value of $q$ is $q_{75} < 2.$ This is confirmed in simulations and theory and in a DIII-D locked mode disruption database. The $q_{75} < 2$ criterion is valid at high $β$ as well as at low $β.$ A very important feature of RWTMs is that they produce major disruptions only when the $q_{75} < 2$ criterion is satisfied. If it is not satisfied, or if the wall is ideally conducting, then the mode does not produce a major disruption, although it can produce a minor disruption. Feedback, or rotation of the mode at the wall by complex feedback, can emulate an ideal wall, preventing major disruptions. The $q_{75}$ criterion is analyzed in a linear simulations, and a simple geometric model is given.
title Prevention of resistive wall tearing mode major disruptions with feedback
topic Plasma Physics
url https://arxiv.org/abs/2411.13256