A numerical model for stability considerations in HTS magnets

Jorma Lehtonen (Corresponding Author), Risto Mikkonen, Jaakko Paasi

Research output: Contribution to journalArticleScientificpeer-review

19 Citations (Scopus)

Abstract

We propose that in an HTS application, stability is lost more likely because of a global increase in temperature caused by heat generation distributed over the whole coil than because of a local normal zone which starts to propagate. For consideration of stability in HTS magnets, we present a computational model based on the heat conduction equation coupled with Maxwell's equations, whereby analysis can be performed by using commercial software packages for computational electromagnetics and thermodynamics. For temperature distribution inside the magnet, we derive the magnetic field dependent effective values of thermal conductivity, specific heat, and heat generated by electromagnetic phenomena for the composite structure of the magnet, while cooling conditions and external heat sources are described as boundary conditions. Our model enables the magnet designer to estimate a safe level of the operation current before a thermal runaway. Finally, as examples, we present some calculations of the HTS magnet with ac to review the effects of slanted electric field-current density E(J) characteristics and high critical temperature of HTS materials.

Original languageEnglish
Pages (from-to)251-258
Number of pages8
JournalSuperconductor Science and Technology
Volume13
DOIs
Publication statusPublished - 1 May 2000
MoE publication typeA1 Journal article-refereed

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