Cryocooler based test setup for high current applications

Abstract

A cryo-cooler based cryogenic test setup has been designed, fabricated, and tested. The setup incorporates two numbers of cryo-coolers, one for sample cooling and the other one for cooling the large magnet coil. The performance and versatility of the setup has been tested using large samples of high-temperature superconductor magnet coil as well as short samples with high current. Several un-calibrated temperature sensors have been calibrated using this system. This paper presents the details of the system along with results of different performance tests.

Solenoid from Experimental HTS tape for Magnetic Refrigeration

“…The heat transfer along the strings to the top of the solenoid does not exceed 0.05 W. The heat input due to 20 measuring leads (manganin, diameter 0.05 mm) is about 5 mW. The total heat transfer to the 2-nd stage of cryocooler over two HTS current leads is 200 mW [16]. Thus, the total heat transfer to the 2-nd stage of the cryocooler is less than 400 mW.…”

“…The second section is made of HTS tapes -from the 1st stage of the cryocooler to the solenoid 11 terminals. Calculations and optimization of uncooled current leads are discussed in detail in [15,16]. For copper, the optimal ratio between the current I, the length L and the cross section S is:…”

“…In accordance with this ratio for = 25 cm and = 200 A the cross section should be S ~ 12.5 mm 2 . In the absence of current, the heat input to the first stage is Q ≈ 4.9 W. Taking into account the temperature distribution over the current lead [16] at an operating current of 150 A, Q ≈ 7 W per one current lead. Thus, the total heat inflow to the 1-st stage of the cryocooler with the operating current 150 A is Q ≈ 21 W.…”