ABSTRACT
This chapter considers the experimental methods of "inverse" Electron paramagnetic resonance (EPR) imaging and their application for the investigation of high-temperature superconductors. Magnetic fields with the configuration are considered as "endless" cylinders. Nonuniform magnetic fields are expressed as a function of the azimuthal angle θ and of the distance from the symmetry axis r. To determine the magnetic field created by high-temperature superconductors (HTS), some "point" paramagnetic samples were placed in the resonator of an EPR spectrometer together with the superconducting sample under investigation. Therefore, EPR imaging may be useful for the investigation of HTS, and, in particular, for the investigation of nonuniformity of the magnetic field not far from HTS. The experiments show that any interaction of the microwave field with the HTS must not only localize in the surface layer, but also is significantly dependent on the surface state of the sample and its orientation relative to B1.
