| 摘要 |
PURPOSE:To enable a pre-ionization electrode to be lessened in consumption and to generate sparks of light from its wide area. CONSTITUTION:Pre-ionization electrode pairs 12 composed of pin-shaped pre- ionization electrodes 10 and fan-shaped pre-ionization electrode 11 are provided on the lengthwise sides of a second main electrode confronting a first main electrode. The tip of the fan-shaped pre-ionization electrode 11 is stepped to enable its part 11a, which confronts the tip 10a of the pin-shaped pre-ionization electrode 10, to be the arc of a sector. The sector part 11a is provided adjacent to the primary electrode 2. |
