ABSTRACT
A peak field of 1200 T was generated by the electromagnetic flux-compression (EMFC) technique with a newly developed megagauss generator system. Magnetic fields closely up to the turn-around peak were recorded by a reflection-type Faraday rotation magnetic-field optical-fiber probe. The performance was analyzed and compared with data obtained by the preceding EMFC experiments to show a significant increase in the liner imploding speed of up to 5 km/s.
ABSTRACT
The maximum magnetic field obtained by the electro-magnetic flux compression technique was investigated with respect to the initial seed magnetic field. It was found that the reduction in the seed magnetic field from 3.8 T to 3.0 T led to a substantial increase in the final peak magnetic field. The optical Faraday rotation method with a minimal size probe evades disturbances from electromagnetic noise and shockwave effects to detect such final peak fields in a reduced space of an inner wall of the imploding liner. The Faraday rotation signal recorded the maximum magnetic field increased significantly to the highest magnetic field of 985 T approaching 1000 T, ever achieved by the electro-magnetic flux compression technique as an indoor experiment.
ABSTRACT
The time-dependent spatial distribution of magnetic fields generated by the electromagnetic flux compression technique is investigated, with emphasis on the dynamical processes of an imploding liner. The developing magnetic field distribution in space and time is determined by a three-dimensional implosion process of the liner that is settled in a primary coil, using an advanced numerical calculation.
ABSTRACT
The precision of the values of a magnetic field generated by electromagnetic flux compression was investigated in ultra-high magnetic fields of up to 700 T. In an attempt to calibrate the magnetic field measured by pickup coils, precise Faraday rotation (FR) measurements were conducted on optical (quartz and crown) glasses. A discernible "turn-around" phenomenon was observed in the FR signal as well as the pickup coils before the end of a liner implosion. We found that the magnetic field measured by pickup coils should be corrected by taking into account the high-frequency response of the signal transmission line. Near the peak magnetic field, however, the pickup coils failed to provide reliable values, leaving the FR measurement as the only method to precisely measure extremely high magnetic fields.
