Magnetic fields are produced in the 10–15 megagauss range by use of high explosives which compress the flux obtained from initial fields of approximately a hundred thousand gauss. The fields described here occupy a cylindrical volume and are essentially axial. A typical field might have these general characteristics: Peak field 14 megagauss; 2 μsec duration from 10–14 megagauss; field volume around peak, 6 mm diameter, 50 mm estimated length.

Articles you may be interested inMicroscopic Faraday rotation measurement system using pulsed magnetic fields Rev. Sci. Instrum. 80, 093705 (2009); 10.1063/1.3229820Precise measurements of Faraday rotation using ac magnetic fields Am.A method is described for making Faraday rotation measurements simultaneously over most of the visible spectrum at magnetic fields in the megagauss range. The fields are produced by explosive-driven magnetic flux compression systems and typically reach 1.2 MG in a few tens of microseconds. The optical train consists of an explosive white light source, polarizer, sample, analyzer, and a sweeping image spectrograph. The technique is applicable to solid or liquid samples. Verdet coefficients are given for LiF, H20, and fused quartz over the wavelength range from about 4000 to 6300 A. The coefficients generally agree to within ±2% with previously published values except for fused quartz for which the present values are somewhat higher at the short wavelength end.

Rapidly varying magnetic fields with peak values in the range from 1 to 5 MG are measured by use of a sweeping image spectrographic method. Atomic spectral lines from an exploding wire light source situated in the experimental region are recorded as the magnetic field varies in a few microseconds from a moderate initial value of a few tens of kilogauss to the peak values. Field measurements are generally accurate to within 2–3% as determined by the consistency of measurements made from several different spectral lines. The sodium D lines and the indium I 4102 Å line have proven to be exceptionally useful for field determinations. The highest field determined to date by this method is 5.1 MG, corresponding to a measured separation of 164 Å between the centers of the shorter and longer wavelength doublets which the NaD lines assume in very high fields. The doublets, of approximately 4 Å separation, are not themselves resolved.

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The excitation spectrum of a free exciton in GaSe has been measured in magnetic fields up to nearly 200 T. The measured spectrum compares favorably with a theoretical calculation done within the effective-mass approximatio'n, consistent with a recent interpretation that the mass anisotropy is smail, p~~/p "=' 1.

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