Experimental study on a conduction cooling system for a HTS NMR magnet

In, Sehwan; Hong, Yong-Ju; Yeom, Hankil; Ko, Jong Soo; Kim, Hyo-Bong; Park, Seong-Je; Yoon, Sanghyun; Cheon, Kyekeun; Jang, Jae Young; Hwang, Young Jin; Lee, SangGap

doi:10.1109/tasc.2017.2656383

Cited by 1 publication

(3 citation statements)

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“…The HTS wire is wound in the shape of double pancake (DP) as a unit [26], and the DPs are stacked together to form a coil. The DP is wound on a stainless steel (SS) former.…”

Section: Hts Wire and Double Pancakementioning

confidence: 99%

“…The basic cooling strategy for this 14 T HTS magnet is like most of other conduction-cooled magnets [20,26,[45][46][47][48]: as introduced in section 2, there is a copper sheet between every two pancakes of a DP unit; the coils will be cooled by the copper sheets, through flexible oxygen-free copper strands [20,48], and to the 2nd stage of the cold head (multiple copper strands will connect DP copper sheets at the coils end and gather onto the cold head end); to reduce the thermal radiation into the coils, an aluminum thermal shield is employed and connected to the 1st stage of the cold head; multi-layer insulation is attached on the outer surface of the thermal shield for radiation reduction on the thermal shield.…”

Section: Cooling Strategymentioning

confidence: 99%

“…The rest of the thermal load from suspension, current lead, thermal radiation, wiring etc is estimated below 1.5 W [20,26,[45][46][47][48]. Take the cryocooler RDK-415D from SHI (Sumitomo Heavy Industries, Ltd) for example, the temperature of the 2nd stage will therefore reach about 5 K at 2.5 W (50 Hz), which is acceptable for the HTS magnet.…”

Section: Ohmic Heating Of Hts Jointsmentioning

confidence: 99%

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Key designs of a short-bore and cryogen-free high temperature superconducting magnet system for 14 T whole-body MRI

Roell

2021

Supercond. Sci. Technol.

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A 14 T whole-body magnetic resonance imaging (MRI) magnet is designed with Bi2223 high temperature superconducting (HTS) wire. Owing to the large critical current and large critical tensile strength of the wire type HT-NX at ultra-high field, the magnet is optimized in a compact shape with length of 1.9 m and outer diameter of 1.3 m. It is in the form of stacked double pancakes (DPs) with total wire consumption of 455 km. The DPs with various inner and outer radii enable the electromagnetic design to obtain highly homogeneous field of 1.5 ppm over 400 mm diameter of spherical volume (DSV). Hoopstress by winding process, thermal contraction and Lorenz force is calculated and below the wire strength specification. Considerable reduction of screening current effect in MRI magnet application is proved by a calculation example. Field homogeneity as it is influenced by various systematic tolerances and random geometric tolerances is numerically estimated, for further design optimization and design of shimming system. Iron room for passive shielding with dimension of 5 × 5 × 10 m is found to be with wall thickness of around 30 cm to effectively contain the 5-Gauss field to the wall surface. Cooling strategy for cryogen-free technique is proposed and the magnet coils temperature is calculated as below 8 K based on the estimation of joint Ohmic heating power of 1.0 W. Quench protection adopts circuit subdivision and dumping resistors to restrict the maximum voltage below 1.9 kV. No-insulation technique for the quench protection is also discussed. Some other wire candidates like REBCO and Nb3Sn for development of such ultra-high field MRI magnets are commented.

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“…The HTS wire is wound in the shape of double pancake (DP) as a unit [26], and the DPs are stacked together to form a coil. The DP is wound on a stainless steel (SS) former.…”

Section: Hts Wire and Double Pancakementioning

confidence: 99%