Experimental studies on thermal behavior of 6 Tesla cryogen-free superconducting magnet system

Abstract

Peformance test and thermal analysis of conduction-cooled optimized current leads at nonoptimum operation AIP Conference Proceedings 1434, 597 (2012) Inter University Accelerator Centre Aruna Asaf Ali Marg, New Delhi, 110067, India ABSTRACT A 6 T cryogen-free superconducting magnet system (CFMS) with warm bore has been designed, built and tested for carrying out physical property measurements at high magnetic field. The CFMS has a vertical Φ 50 mm clear room temperature working bore. A two-stage GM-cryocooler of 35 W at 50 K and 1.5 W at 4 K cooling capacity has been used to cool the thermal radiation shield, hybrid current leads and the NbTi magnet. The magnet was charged to 102 A, which produced a field of 6 T, in less than 20 minutes. The outer surface temperature of magnet rose from 3.3 K at zero current to 3.9 K at 102 A current. The thermal link between cold head and magnet greatly influences the excitation rate and the stability of the magnet. Based upon our thermal analysis on the magnet system, an experimental study has been carried out on the thermal behavior of the magnet during its operation. A novel technique has been used for connecting the high temperature superconducting current leads to the magnet so as to reduce both electrical and thermal contact resistance at the 2 nd stage of the cryocooler. This paper briefly describes the design, development and results of experimental studies of thermal behavior of the system.

Signature of strong localization and crossover conduction processes in doped ZnO thin films: synergetic effect of doping fraction and dense electronic excitations

“…The optical properties of pristine and irradiated thin films were studied using UV-VIS-NIR spectroscopy with a UH-4150 spectrometer. Further, the SHI's effect on Ga doped thin films was investigated for the electrical conduction mechanism using the temperaturedependent resistivity measurements in the temperature range of 10-300 K using a home-made set-up named as variable temperature insert cryogen-free magnet system [34][35][36]. The temperature-dependent resistivity measurements on pristine films could not be performed due to their high resistive nature (resistance in the order of Mω).…”

Peformance test and thermal analysis of conduction-cooled optimized current leads at non-optimum operation

“…In this paper, we briefly describe the thermal behavior of optimized copper leads for non-optimum operating current to understand the phenomenon of conduction-cooled lead required for the development of a 6 T cryogen free magnet system at our institute [9][10]. We have estimated the heat load per unit current for different non-optimum currents and compared them with the experimentally measured values.…”