Angular Measurements of HTS Critical Current for High Field Solenoids

Abstract

An experiment is in the works at Fermilab to confirm that ionization cooling is an efficient way to shrink the size of a muon beam. This would pave the way for Muon Collider machines, which however require in their last stages of acceleration very high field solenoids. The use of high temperature superconducting materials (HTS) is being considered for these magnets using Helium or higher temperature refrigeration. A sample holder was designed to perform critical current (I c ) measurements of HTS conductors under externally applied magnetic fields varying from zero to 90 degree with respect to the c-axis. This was performed in an ample range of temperatures and magnetic field values. A description of the test setup and results for (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O x (BSCCO-2223) tapes, and Second Generation HTS in the form of 348 superconductor are presented.

Study of HTS Wires at High Magnetic Fields

“…8 and 9 for the 2G SCS 4050 and the 1G hermetic tapes, using for data at 4.2 K both FNAL and NIMS results. For the 1G tape, a linear field dependence with a slope increasing with temperature had been produced for this ratio [11]. The NIMS data show a reasonably flat field dependence at 4.2 K (Fig.…”

“…Fig. 4 shows I c results at 4.2 K for the HTS wires as a function of magnetic field as measured at NIMS and at FNAL [11]. For the tapes both the parallel and perpendicular field configurations were used.…”

“…The sample, supported in its middle part by G-10, was soldered within a groove on two Cu half cylinders using a splice length of 12 mm at each sample end to control contact resistance and heating power. The sample holder was placed at the desired angle within cylindrical holes in the probe Cu lugs [11]. The distance between the voltage taps was of 10 mm.…”

“…This is due to the hysteretic I c (B) behavior [18] of BSCCO-2223 when tested in increasing (FNAL) and decreasing (NIMS) magnetic field. [11]. The tapes were tested both in parallel and perpendicular fields.…”

“…The I c angular dependence was measured at FNAL at temperatures from 4.2K to 33 K up to 15 T, while providing up to 1400 A of current to a 2G sample by SuperPower (SP). To complement similar studies on two HTS conductors by American Superconductor (AMSC) [11], the latter plus a sample by SP were tested at 4.2 K in parallel and perpendicular field configurations up to 28 T at NIMS. …”