Abstract: A control circuit has a three-phase modulation operation mode under which a three-phase modulation signal is output to an inverter circuit as a pulse width modulation signal, a two-phase modulation operation mode under which a two-phase modulation signal is output to the inverter circuit as the pulse width modulation signal, and a transitional operation mode under which one of the three-phase modulation operation mode and the two-phase modulation operation mode is switched to the other. The control circuit transitions to the transitional operation mode in response to a reference signal set in advance, and switches an operation by outputting to the inverter circuit, a transition modulation signal with a mixture ratio between the three-phase modulation signal and the two-phase modulation signal being gradually changed in a predetermined electrical angle interval unit.

Abstract: A heating apparatus suitable for use in medical heat treatment of an affected portion of a human body employs a cavity resonator supplied with high-frequency energy from a high-frequency power supply unit. The cavity resonator comprises a cavity formed of a conductive material and at least one inner protrusion in said cavity generating a standing wave electric field for heating a body or body part introduced into the cavity. The inner protrusion may be a separate conductor or may be formed by deforming a portion of the conductor forming the cavity. A highly concentrated standing wave electric field and a surrounding electromagnetic field are produced in the cavity resonator when it is energized from the high-frequency power supply unit. The concentrated standing wave electric field intensively heats a desired local portion of the body and deep parts of the body may be heated satisfactorily.

Abstract: The present invention relates to a method for measuring three-dimensional spatial magnetic field distributions used particularly in measuring the magnetic field distribution in a small spatial region such as a leakage magnetic field of a magnetic head and the object thereof is a measuring method capable of measuring a high frequency magnetic field in the small spatial region with a high precision.

Abstract: A superconducting electron beam generator comprising a cavity resonator situated in a refrigerator and containing a superconductive metal member fixed on the cavity end plate, a tip of which member is disposed at the strongest point of a high frequency electric field formed in the cavity. A high quality and high energy coherent electron beam is emitted by the electric field from the tip of the metal member along an axis of the cavity and derived through a minute hole formed through the opposite end plate. This superconducting electron beam generator is particularly suitable for a high resolution electron microscope, a high quality X-ray generator, a crystallographic electron beam apparatus and the like.