원문정보
초록
영어
Discrepancy between a power supply current and an actual “spiral” coil current makes the conventional 4-probe measurement of a critical current (Ic) of a no-insulation (NI) high temperature superconductor (HTS) coil inaccurate and time-consuming. This paper presents a fast and accurate approach for Ic measurement of NI HTS coils. With an NI HTS coil energized at a constant ramping rate, a complete analytic expression for the spiral coil current was obtained from a first-order partial differential equation that derived from an equivalent circuit model of the NI coil. From the analytic solution, both spiral coil current and radial leak current can be obtained simultaneously, which enables fast and accurate measurement of the NI coil Ic. To verify the proposed approach, an NI double-pancake (DP) coil, wound with GdBCO tapes of 6 mm × 0.1 mm, was constructed and its Ic was repeatedly measured with various ramping rates in a bath of liquid nitrogen at 77 K. The measured results agreed well with the calculated ones, which validates the proposed approach to measure Ic of an NI HTS coil.
목차
1. INTRODUCTION
2. PROBLEM IDENTIFICATION IN CONVENTIONAL 4-PROBE Ic MEASUREMENT
2.1. Preparation of Coil
2.2. Discrepancy between Power Supply Current and Actual Coil Current
3. NEW APPROACH: CONSTANT RAMPING AND LEAK CURRENT CORRECTION
3.1. Equivalent Circuit Model for NI Coil
3.2. Charging Analysis of an NI Coil with a Constant Ramping Rate
3.3. Characteristic Resistance (Rc) Estimation
3.4. Leak Current Correction for Critical Current Measurement
4. CONCLUSION
ACKNOWLEDGMENT
REFERENCES