Development of reliable 70 T pulsed magnets

Abstract

A capacitor-driven pulsed magnet coil has been designed to generate fields in the 70-75 T range, with a life expectancy of at least 100 pulses, thus qualifying as a '75 T class user magnet'. The bore is 10 mm and the rise time used in our experiments is 4 ms. The coil consists of two coaxial sections: the inner section, where stresses are highest, is made with CuNb microcomposite wire and optimized Zylon reinforcement; the outer section is made with soft copper and glass fibre composite. In the inner section, the stress in each layer is self-contained, while the stresses induced in the outer section are transmitted to a thick shell made from steel and carbon fibre composite. The cross section of the copper wires is adjusted to redistribute the heating evenly between the inner and the outer section. Another innovative design feature is a system for axial compression that can be easily retightened during coil training. Two nearly identical coils were manufactured and tested to 72 T; this is a limit imposed due to overheating when using our 10 kV, 0.5 MJ capacitor bank (at an energy of 380 kJ). At 75 T, the calculated von Mises stress in the Zylon composite is 2.6 GPa, well below the UTS of more than 3 GPa, and the CuNb wire is still in an elastic state.

Pulsed magnetic fields as a probe of self-assembled semiconductor nanostructures

“…In general, it is clear that the stronger the spatial confinement of the carriers, the smaller the diamagnetic shift. We illustrate how this may be exploited in the study of self-assembled QDs with the results obtained for InAs dots grown on ð1 0 0Þ and ð3 1 1ÞB GaAs substrates at the University of Nottingham [4,11,12]. The idea behind the experiment is illustrated in Fig.…”

“…Photoluminescence (PL) experiments are conducted in 50 T pulsed field coils developed in the laboratory [8] in combination with a 5 kV; 600 kJ capacitor bank [9], though a 70 T user coil connected to a 10 kV; 500 kJ capacitor bank has recently become available [10]. Both 4 He bath and flow cryostats are used for PL experiments making temperatures between 1.5 and 200 K accessible.…”

Simulation study of wake field excitation in interaction of intense laser and magnetized plasma: Half-sine pulse shape (HSPS) and trapezoid pulse shape (TPS)

“…A jet of fast electrons flowing along the laser propagation direction [21] or a nonlinear current of the plasma electrons [22] is usually used to generate magnetic fields. Generation of magnetic fields up to 70 T using the technology of pulsed magnets is also reported [23]. Ultra-intense magnetic fields have a significant effect on particle transport, propagation of laser pulses and laser beam self-focusing.…”

Geometry Optimization of Pulsed Inductors

“…Therefore scientists often turn to low energy consumption pulsed technologies and pulsed magnetic fields that often are sufficient enough for carrying out most of the experiments where these fields have to be applied. A relatively simple system included a capacitor bank, a pulsed switch and an inductor can be used for pulsed magnetic field generation up to 60-70 T [2].…”