The present invention relates to an electron gun cathode mount adapted at one end to secure a thermionic cathode and at the other end to be connected to an attachment member, wherein the electron gun cathode mount is structured so as to be capable of, when in use, reducing heat transfer from the thermionic cathode to the attachment member, and the material forming the electron gun cathode mount has a thermal conductivity of less than 10 Wm.sup.?1K.sup.?1 at the operating temperature of the thermionic cathode in a direction from the thermionic cathode to the attachment member. The present invention also relates to an electron gun assembly having the electron gun cathode mount installed therein.

The invention provides a power supply module and a charged particle beam device that are capable of reducing ripple noise. A high-voltage generation circuit 101 includes booster circuits CPa and CPb of two systems that are configured to be symmetrical to each other, and performs a boosting operation by using a capacitive element and a diode in the booster circuits CPa and CPb of the two systems. The high-voltage generation circuit is housed in a housing and a reference power supply voltage is applied thereto. A left electrode 102a is fixedly provided in the vicinity of one of the booster circuits CPa and CPb of the two systems in the housing, and a right electrode 102b is fixedly provided in the vicinity of the other of the booster circuits CPa and CPb of the two systems in the housing. A stray capacitance adjustment circuit 100a adjusts capacitance values of stray capacitances of the booster circuits CPa and CPb of the two systems by electrically controlling an electrical connection characteristic between the left electrode 102a and the reference power supply voltage 104 and an electrical connection characteristic between the right electrode 102b and the reference power supply voltage 104.

The present invention relates to an electron gun cathode mount adapted at one end to secure a thermionic cathode and at the other end to be connected to an attachment member, wherein the electron gun cathode mount is structured so as to be capable of, when in use, reducing heat transfer from the thermionic cathode to the attachment member, and the material forming the electron gun cathode mount has a thermal conductivity of less than 10 Wm.sup.1K.sup.1 at the operating temperature of the thermionic cathode in a direction from the thermionic cathode to the attachment member. The present invention also relates to an electron gun assembly having the electron gun cathode mount installed therein.