| 摘要 |
PCT No. PCT/GB89/00505 Sec. 371 Date Dec. 27, 1990 Sec. 102(e) Date Dec. 27, 1990 PCT Filed May 11, 1989 PCT Pub. No. WO89/11770 PCT Pub. Date Nov. 30, 1989.A contactless heating apparatus for thin filaments comprises means to linearly support a length of filament (10), an induction coil (11) provided adjacent to the filament with its axis substantially parallel to the length of filament, a source (15) of alternating current in the frequency range from HF to UHF connected to the coil, and a conducting rod (16) connected to one of the end turns of the indication coil (11) and disposed substantially parallel to the length of filament (20); the arrangement being such that heating of the filament occurs adjacent to the conducting rod. The filament (20) is run through a vertical cylindrical chamber (21) in which a reducing atmosphere is maintained. The coil (11) is non-uniform in diameter, the diameter being larger at the end (14) to which the rod (16) is attached and the end (12) of the coil opposite to that to which the rod is attached is earthed (13). The rod (16) may be shaped such that the separation between rod and filament varies along the length of the rod to thereby vary the temperature profile along the heated portion of the filament. The AC power source (15) used is a Class C oscillator valve located in the induction furnace. This power source is rich in harmonics. |
