MCP unit, MCP detector and time of flight mass spectrometer

An MCP unit comprising:

• a micro-channel plate, for releasing secondary electrons internally multiplied in response to incidence of charged particles, arranged on a plane that intersects a predetermined reference axis, said micro-channel plate having an incident surface upon which the charged particles are incident, and an exit surface that opposes the incident surface and emits the secondary electrons;
• a first electrode being in contact with the incident surface of said micro-channel plate, said first electrode being set to a predetermined potential;
• a second electrode being in contact with the exit surface of said micro-channel plate, said second electrode being set higher in potential than said first electrode;
• an anode arranged in a position where the secondary electrons released from the exit surface of said micro-channel plate reach, in a state to intersect the reference axis, said anode being set higher in potential than said second electrode;
• and
• an acceleration electrode arranged between said micro-channel plate and said anode such that a shortest distance to said anode is longer than a shortest distance to the exit surface of said micro-channel plate, said acceleration electrode being set higher in potential than said second electrode and having a plurality of openings which permit passing of the secondary electrons migrating from the exit surface of said micro-channel plates toward said anode.