We report on the design and performance of a megagauss generator at the Humboldt High Magnetic Field Centre. The installation uses the fast capacitor discharge into single-turn coils to produce microsecond pulses of 260 T in 8 mm diameter suitable for low-temperature experiments and 310 T in 5 mm diameter. Simple concepts are applied to substantiate crucial design principles for the generator and the choice of components. The implementation of a high-power/low-inductance circuit operated at 60 kV and other technical questions are discussed in detail. The analysis of experimental field and current data is based on numerical simulations of the magnetic pressure and the nonlinear flux diffusion. It was carried out in order to investigate the limitations and characteristics of the Berlin generator in particular and the single-turn coil technique in general. The paper focuses primarily on field, generator and coil parameters, which can be used for performing routine, reproducible scientific experiments at low temperatures.
When it comes to education for mobile pastoralists, Mongolia is an exceptional case. Until fifty years ago, herders comprised the majority of the Mongolian population. Although a satellite of the Soviet Union, the Mongolian People's Republic was a state in which mobile pastoralism was not challenged, and herders were not constructed as social outcasts. Equally exceptional was the country's modernisation, witnessed in its decided alignment with equal opportunities. In Mongolia, it was not 'nomadism' that was associated with backwardness, but illiteracy. Policy-makers aimed to combine spatial with social mobility by building schools further and further out in the grasslands, employing locals as teachers, and fostering interplay between modern formal education and extensive animal husbandry. Yet after 1990, when development discourse pigeon-holed post-socialist Mongolia as a Third World country, the so-called shock therapy led to severe cuts in education. Herders were essentialised as 'nomads', which caused donor-driven policies of educational planning to construe pastoralists as challenges. Ironically, during the initial decade of Education for All, the younger generation had-for the first time in Mongolia's history-less educational opportunities than their parents. This article discusses narratives of inclusion and the political consequences of ascribed social identities.
A small megagauss generator which produces 110 T by fast semi-destructive capacitor discharge into a single-turn coil of 10 mm diameter is described. For spectroscopic applications the pulses are adequately resolved by 8 - 12 bit, 200 - 1000 MSa data recording systems. The technical implementation of the 60 kV discharge circuit with a total inductance of less than 26 nH, not including the field coil, is discussed in detail. The performance is characterized in terms of the oscillatory circuit parameters R, L and C with brief references to more fundamental studies on transient field phenomena. Safety features as well as the organization and handling of control units and data recording systems are explicitly described to demonstrate the applicability of the generator.
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