| 摘要 |
PROBLEM TO BE SOLVED: To irradiate an electromagnetic wave into a discharge tube efficiently without reflection of the electromagnetic wave. SOLUTION: This is equipped with an electromagnetic wave irradiation part 18 in which the electromagnetic wave transmitted from a power supply part 12 via an electromagnetic wave transmission part 14 is introduced and irradiated, and the discharge tube 22 to discharge and emit light by plasma formed by receiving the electromagnetic wave irradiated from the electromagnetic wave irradiation part 18, the electromagnetic irradiation part 18 has an inner conductor 19 to introduce the electromagnetic wave, and an outer conductor 20 to cover the inner conductor 19, the discharge tube 22 has sealed parts 24, 25 in which conductor assemblies 26, 27 are sealed inside. In the case a length of a retaining region retained in the electromagnetic wave irradiation part 18 out of the discharge tube 22 is made L1, the length of a discharge region exposed outside from the electromagnetic irradiation part 18 is made L2,εis made a dielectric constant of the discharge tube 22, andλis made a wavelength of the electromagnetic wave, on condition that the inner conductor 19 is extended up to a position to cover the retaining region, relationships of L1>λ/8(ε)<SP>1/2</SP>and L2<λ/4(ε)<SP>1/2</SP>are satisfied. COPYRIGHT: (C)2010,JPO&INPIT
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