Performance of conduction-cooled HTS tape with the aid of solid nitrogen–liquid neon mixture

Construction of high-temperature superconducting magnets typically involves impregnation of a coil in a liquid medium, such as epoxy, which is then solidified. This impregnation provides mechanical integrity to the magnet and facilitates heat transfer. The choice of material used for impregnation requires careful consideration of the material properties and the performance requirements in order to ensure optimal magnet operation. This paper offers a comprehensive educational resource on this topic, reviewing the literature available on materials for magnet impregnation. A detailed explanation of considerations for selecting an impregnation material are presented, along with a review of several types of materials and their characteristics as reported in the literature. The materials are compared, and their suitability to different applications is discussed. Topics for future research are suggested.

Section: Solid Cryogenssupporting

confidence: 71%

Section: Solid Cryogensmentioning

confidence: 67%

Review of materials for HTS magnet impregnation

Feldman,

Stautner,

Kovacs

et al. 2024

“…The recovery time (3.1 s) in the former was almost the same as that (3.2 s) in LN2 (77 K). However, in the latter, the recovery time was 50% faster than that in LN2, which suggested that the thermal contact was improved because SN2 behaved as a large heat capacitor and LN2 as a thermal exchanger between the cold body and the SFCL module [14,15]. To summarize, the study results clearly demonstrated that the electrical/thermal properties of the SFCL module may be improved by impregnating with SN2 as a large heat capacitor if the thermal contact is improved by using a mixed solid-liquid cryogen.…”

Section: Resultsmentioning

confidence: 99%

The design, fabrication and testing of a cooling system using solid nitrogen for a resistive high-T_csuperconducting fault current limiter

Song

Kim

et al. 2008

In general, conventional high-T c superconducting fault current limiters (SFCLs) are operated by cooling systems with a liquid cryogen, such as liquid nitrogen (LN2). However, in the fault mode, LN2 evaporates because of joule heating in the SFCL module, so the SFCL system experiences an enormous increase in nitrogen gas volume. In this case, the thermal stability and protection of the system become the primary concerns for the design of the SFCL cooling system. In order to enhance the thermal stability and safety of the system, an SFCL cooled by solid nitrogen (SN2) as a large heat capacitor has been proposed as an alternative. In this paper we report the quench/recovery characteristics of a YBCO-coated conductor (CC) evaluated in an SN2 cooling system for the SFCL. A feasibility study is also conducted on the reference design codes and thermal requirements for the optimal design of the SN2 cooling system. The results demonstrate that the improved thermal contact obtained between the SN2 cooling system and the SFCL module renders the proposed system a suitable cryogen for the SFCL module. Detailed experimental results for the LN2 and SN2 cooling systems are presented and discussed.

“…Also as with the SN2 plot in figure 2, the cold chamber temperature remained at 35.6 K for a period of time, here, ∼0.5 day, owing to the latent heat (8.3 J cm −3 ) of the SN2 phase. This SN2 thermal mass enhancer design concept for the LHe-free magnets has been studied by others [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. It should be noted here that GE was the first manufacturer in the early 1990s to market LHe-free superconducting MRI magnets when it introduced all-Nb 3 Sn, cryocooled MRI magnets operating at 10 K, the practical upper temperature for Nb 3 Sn [20].…”

Section: Magnet Performancementioning

confidence: 97%

Towards liquid-helium-free, persistent-mode MgB₂MRI magnets: FBML experience

Iwasa

2017

In this article I present our experience at the Magnet Technology Division of the MIT Francis Bitter Magnet Laboratory on liquid-helium (LHe)-free, persistent-mode MgB2 MRI magnets. Before reporting on our MgB2 magnets, I first summarize the basic work that we began in the late 1990s to develop LHe-free, high-temperature superconductor (HTS) magnets cooled in solid cryogen—I begin by discussing the enabling feature, particularly of solid nitrogen (SN2), for adiabatic HTS magnets. The next topic is our first LHe-free, SN2-HTS magnet, for which we chose Bi2223 because in the late 1990s Bi2223 was the only HTS available to build an HTS magnet. I then move on to two MgB2 magnets, I and II, developed after discovery of MgB2 in 2000. The SN2-MgB2 Magnet II—0.5-T/240-mm, SN2-cooled, and operated in persistent mode—was completed in January 2016. The final major topic in this article is a tabletop LHe-free, persistent-mode 1.5-T/70-mm SN2-MgB2 “finger” MRI magnet for osteoporosis screening—we expect to begin this project in 2017. Before concluding this article, I present my current view on challenges and prospects for MgB2 MRI magnets.