| 摘要 |
PURPOSE:To prevent temperature rise of emitter chip and ionization chamber by employing a structure that the gas supplied from a gas supply pipe reaches an aperture passing through the space between double walls forming the ionization chamber. CONSTITUTION:The ionization chamber wall is formed by the double walls of external wall 11 and internal wall 12, the space 1B exists between these double walls and this space 1B is connected with an ionization gas supply pipe 6. An aperture 1A is provided through the ionization chamber wall forming the double walls. With each such structure, the gas flows in the sequence of gas supply pipe 6 space 1B aperture 1A and does not flow directly into the ionization chamber 2 and the gas flowing first is remaining here. Therefore, even when a large amount of gas is supplied, the ionization chamber 2 is kept at a low temperature, not allowing temperature rise at the emitter chip 5 and insulating part 4. |
