To provide a Faraday cup ammeter receiving no charge of charged particles which are charged on a particle collecting section.
The perimeter of the particle collecting section 11 is covered by a conductive member 13 and fixed by a plurality of conductive pins 15. The particle collecting section 11 and the conductive member 13 are electrically insulated by an insulating material 17, and a conductive cage 19 is disposed around the insulating material 17. An ammeter 23 for detecting a charge collected by the particle collecting section 11 is disposed between the conductive cage 19 and an earth 21. A switch (charge discharging mechanism) 27 for switching on/off states of a connection is disposed in the middle of a lead wire 25. An integral current value charged on the particle collection section 11 is calculated by the ammeter 23.
OKUDA HIROSHI
KIMOTO SHIGERU
