-Within the Siemens current limiter program a 100 kVA functional model has been realized and tested successfully. According to the modular concept of the limiter the functional model is assembled of ten switching elements. YBCOfilms with a thickness of 250 nm and a critical current density above 2x106 A/cm2 are deposited by thermal coevaporation (TU Munich) on 4" sapphire wafers. To support homogeneous switching the superconducting film is covered with a 100 nm Au -shunt layer. Good current limiting performance is achieved:The steady limiting current is below the nominal current, the peak fault current increases up to 3 times the nominal current within an action time of one millisecond. The operational recovery time of the limiter, within which the switching elements return to the superconductive state again is about 2 s. Following our limiter program the next step will be a model device with a nominal switching power of 1 MVA.

The Faraday effect usually is regarded as to be caused by one single pass of the incident wave through the volume of a material. This description neglects the magnetooptical interface effects and the magnetooptical consequences of multiple reflections within the medium. A matrix calculation model is presented for calculating consistentely magnetooptical reflection and transmission spectra. This method yields as well the magnetooptical effects of homogeneous materials as the magnetooptical effects of arbitrary successions of multilayer systems including coherent and incoherent multiple reflections and magnetooptical interface effects. The theorem of magnetooptical reciprocity is discussed and it is shown, that optical inhomogeneous materials generally yield six independent measurable magnetooptical effects. A physical model is constructed which can be used to determine free carrier density profiles of ion implanted and diffused semiconductors nondestructively by utilizing the magnetooptical properties of the free carrier plasma. Generalized dispersion relations which are as well valid between the magnetooptical reflection effects as between the magnetooptical transmission effects are given.

One of the most promising technologies for the fabrication of high-T c cables is the ion-beam-assisted deposition ͑IBAD͒ technique. The performance of the superconductors fabricated by IBAD, and the fabrication costs, are to a great extent determined by the critical current densities of the superconductors' grain boundaries. Since, in bicrystalline samples, overdoping has been found to improve the transport properties of grain boundaries in high-T c superconductors, we have explored whether overdoping also enhances the critical currents of IBAD samples. The measurements show that, depending on the critical current density of the superconducting film, J c ͑77 K͒ is increased by factors up to 2.2, also in applied magnetic fields of several tesla.

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I n doping profiles used by modern semiconductor technology exist extremly large gradients of the complex refractive index which produce significant spectra of integral optical reflectivity and transmission by "internal reflection". I n this case the calculus of geometrical optics approximation cannot be used. It is shown, that it is possible to calculate the spatial distribution of the optical constants and the local free carrier concentration, respectively, using the matrices calculation of mult,ilayer structures and the Drude Theory. The concentration profiles which are used for example are present in boron diffused (surface concentration up to No = 3.4 x lo2" and ion implanted (fluence of implanted boron ions: N D ,~ = 10l6 ions/cm2 a t 150 keV) silicon samples. After successive isochronally annealing (700 to 950 "C) the implanted ions are electrical activated as an increasing modified Gauss profile. Another interesting aspect is the question of transmission and reflectance if the direction of wave propagation is changed in connection with the theorem of reciprocity. I n agreement to the theory the integral transmission is symmetrical, but the integral reflection is asymmetrical.I n den in der modernen Halbleitertechnologie iiblichen Dotierungsprofilen traten extrem groBe Gradienten des komplexen Brechungsindex auf, die durch ,,interne Reflexion" signifikante Spektren des integralen optischen Reflexionsvermogens und der Transmission hervorrufen. I n diesem Falle 1a5t sich die geometrisch optische Naherung nicht anwenden. E s wird gezeigt, daB es moglich ist, die raumliche Verteilung der optischen Konstanten und die lokale Konzentrrttion freier Trager unter Benutzung der Matrizenrechnung von Mehrschichtstrukturen und der Drudetheorie zu berechnen. Die Konzentrationsprofile, die als Beispiele betrachtet werden, liegen in Bordiffundierten (Oberflachenkonzentrationen bis zu No = 3,4 x 102O om+) und ionenimplantierten (Dosis der implantierten Borionen: N D , 0 = 10l6 Ionen/cm2 bei 150 keV) Siliziumproben vor. Nach sukzessiver isochroner Temperung (700 bis 950 "C) werden die implantierten Ionen als wachsendes modifiziertes GanlJprofil elektrisch aktiviert. Ein anderer interessanter Aspekt ist die Frage der Transmission und des Reflexionsvermogens, wenn die Richtung der Wellenausbreitung geandert wird im Zusammenhang mit dem Reziprozitatstheorem. I n ubereinstimmung mit der Theorie ist die integrale Transmission symmetrisch, die integrale Reflexion jedoch asymmetrisch.