| 摘要 |
PROBLEM TO BE SOLVED: To increase the number of impurity ions to be discharged outside. SOLUTION: A chamber 40 comprises a gas inlet 40a, a gas outlet 40b and a pore 41 for discharging impurity ions. Gas flowing through the gas inlet 40a flows out of the gas outlet 40b through mainly the vicinity of the pore 41, although part of the gas flows out of the pore 41. The flowing-in gas is primarily ionized by corona discharge generated between a cylindrical electrode 34 and a discharging needle 44. A desired potential gradient is formed by the cylindrical electrode 34 and another electrode 38 between the primarily ionized portion and the pore 41 independently of a corona discharging operation. Subsequently to the primary ionization, an ion molecular reaction is carried out, thereby producing impurity ions, which are discharged outside through the pore 41. |
