Charged particle beam source and charged particle beam system

A charged particle beam source configured to release a charged particle beam aligned with an optical axis, comprising:

• a chamber having a side wall;
• a first unit comprising a supportive insulative member mechanically supporting a cable, a first set of terminals electrically connected to the cable, and a support member comprising a central axis coincident with the optical axis;
• and
• a second unit comprising an emitter for emitting charged particles, a second set of terminals electrically connected to the emitter, an electrode positioned under the emitter and provided with a hole for passage of electrons released from the emitter, and a third terminal electrically connected to the electrode, the second unit configured to be detachably mounted to the first unit;
• wherein the first unit is secured in a through-hole formed in the side wall of the chamber;
• wherein the first unit includes a fourth terminal;
• wherein the first set of terminals is elongated in a direction orthogonal to the optical axis;
• wherein the second set of terminals is elongated in a direction orthogonal to the optical axis when the second unit is inserted into the support member;
• and
• wherein the second unit is configured to be inserted into the support member such that the emitter is placed on the optical axis within the chamber, whereby the first and second sets of terminals are brought into contact with each other and the third and fourth terminals are brought into contact with each other.