RADIOFREQUENCY HEATING OF THIN FILAMENTS

摘要

2074185 9112702 PCTABS00006 A radiofrequency heating apparatus for heating a linearly supported thin electrically conductive filament (10) comprises a coil (15), earthed at one end, located adjacent to the filament; and a source (12) of radiofrequency (RF) signals in the frequency range from H.F. to U.H.F. connected to the coil. A conducting element (16) is connected to the non-earthed end of the coil (15) and arranged to form or lie on the surface of a cylinder (11) through which the filament (10) passes coaxially whereby the heating of the filament occurs within the cylindrical conducting element (16) and the RF signals are amplitude modulated. Preferably the modulation applied to the RF source is within the audio frequency band, conveniently double or single sideband modulation. The source of modulation may be pulsed and preferably the radiofrequency is approximately 13,56 MHz.