Harald Dr Schmidt

Development and test of a 100 kVA superconducting transformer operated at 77 K

High-temperature superconducting (HTS) transformers are very promising candidates for application in electrical power engineering. Their main advantages are reduced size, weight, better efficiency and reduced potential fire and environmental hazards. We have designed, constructed and tested a 100 kVA HTS power transformer operated at 77 K. The nominal primary and secondary currents (voltages) are 18 A (5.6 kV) and 92 A (1.1 kV), respectively. No-load tests, short-circuit tests and load tests proved repeatedly that the transformer has the rated capacity. HTS winding losses of 20.6 W and iron losses of 403 W were measured.

RF-magnetron sputtered lanthanum aluminate buffer layers on silicon

Optimization of the preparation conditions of in situ highly textured thin films of LaAlO3 on silicon (100) substrates, by planar RF-magnetron sputtering, was investigated. The parameters which have been considered for this optimization include: substrate temperature (T), gas pressure (P), the ratio of flow of oxygen to argon O2/Ar (all during sputtering of the layer), and the deposition power. Furthermore, different precleaning and oxidation treatments were applied to the silicon surface in order to remove the amorphous layer of the silicon native oxide (SiO2). This was to enhance epitaxial growth of LaAlO3 layers on silicon.