Detailed cross sectional view of the high field SQUID magnetometer. (1) Heat exchanger, (2) impedance chamber, (3) OFHC copper block, (4) NbTi shields, (5) thermal isolation vacuum chamber, (6) VTR chamber, (7) sample chamber, (8) liquid helium reservoir, (9) electrical feedthrough for impedance chamber, (10) evacuation port for thermal isolation and impedance chamber, (11) pumping line for VTR chamber, (12) manometer and throttle valve, (13) pumping line for sample loading, (14) helium exchange port, (15) Wilson seal for sample loading, (16) Wilson seal for sample movement, (17) gate valve, (18) stepper motor, (19) electrical feedthrough port for heater and thermometer (sample), (20) evacuation port for shield chamber, (21) electrical feedthrough port for heater and thermometer (NbTi shields), (22) electrical feedthrough port for SQUID, (23) radiation baffles, (24) sample rod, (25) superconducting flux transformer, (26) SQUID, (27) second order gradiometer pickup loop, (28) superconducting magnet (7T), (29) liquid helium level sensor, (30) thermal radiation shields, and (31) liquid helium cryostat.
Detailed cross sectional view of the high field SQUID magnetometer. (1) Cold He gas inlet, (2) spacer for the superconducting pickup loop former (lower), (3) bottom cover of the superconducting shield chamber, (4) spacer for the NbTi shields, (5) spacer for the superconducting shield chamber, (6) superconducting pickup loop with former, (7) NbTi shields with non inductive heater, (8) superconducting magnet, (9) superconducting NbTi wire used as thermometer, (10) top flange of the superconducting shield chamber, (11) spacer for the superconducting pickup loop former (upper), (12) thermal isolation vacuum chamber, (13) twisted leads of the gradiometric pickup loop, (14) evacuation and electrical leads port for the shield chamber, (15) SQUID, and (16) superconducting stepdown flux transformer.
Schematic view of the SQUID detection system. (a) Schematic view of the pickup loop and the SQUID input circuit in conventional SQUID magnetometer. (b) Schematic view of the input circuit employed in the present system with two different SQUID sensors with different strengths of coupling. In both cases, it is expedient to connect a superconducting loop parallel to the input coil of the SQUID to avoid frequent unlocking of the flux locked loop electronics by stray magnetic disturbances exceeding the system slew rate.
Magnetic flux profile recorded for the superconducting lead sample with strong and weak coupling to the input coil of the SQUID.
(a) The variation of the sample region temperature with uniform rate of heating and cooling set by the user. (b) Temperature stabilities recorded experimentally while maintaining a constant temperature of 10, 100, 200, and 300 K in the vicinity of the sample region.
Sample transport assembly. (1) Evacuation port, (2) exchange gas port, (3) upper Wilson seal, (4) lower Wilson seal, (5) guide tube, (6) stepper motor, and (7) gate valve.
Schematic arrangement of electronics communicating with the various subsystems of the SQUID magnetometer for the automation of the system. (1) Heater for the superconducting pickup loop, (2) heater for the persistent switch of the superconducting magnet, (3) superconducting magnet, (4) heater for the superconducting shields, (5) thermometers for the superconducting shields, (6) heater and thermometer in the impedance chamber, (7) heater and thermometer in the sample chamber, (8) stepper motor, (9) SQUID sensor.
The magnetic flux profile of the dipole moving through the second order gradiometer pickup loop with coil parameters r = 11.5 mm, b = 0.375 mm, and d = 10.875 mm (nominal).
Recorded SQUID output data for the YIG sphere is fitted to its magnetic moment value of 0.0776 emu to infer the calibration factor of the SQUID magnetometer.
Magnetic flux profiles of the Gd2O3 sample recorded at various temperatures.
Temperature dependent susceptibility (M/H) and inverse susceptibility (H/M) of Gd2O3 sample plotted as a function of temperature.
Article metrics loading...
Full text loading...