| 摘要 |
PURPOSE:To increase the amount of ionization with a chip temperature being suppressed, by supplying a helium gas to the emitter chip end cooled by liquid helium, and drawing ions from the helium, which are cooled, with a drawing electrode. CONSTITUTION:An emitter chip 1 is cooled by a coolant jar 3 into which liquid helium is supplied through a pipe 6, and the helium gas is introduced into the end of the chip via an introduction pipe 13 on which a heat exchanger 14 is arranged intermediately, and ionized to be drawn by a drawing electrode 9, to compose a gas phase ion source. Then, the drawing electrode 9 is mounted on an electrode supporting board 10 through a cylindrical material 11 of thermal good conductor, and liquid nitrogen 16, introduced into the heat exchanger 14 through a pipe 15, is supplied for cooling into the space 12 via a pipe 17. Therefore, heating, due to ion impact, of the drawing electrode 9 is avoided to suppress the temperature rise of the chip 1, and the amount of ionization can be increased.
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