PURPOSE: To minimize drift by forming a vacuum space with whole face of an exciting coil and a magnetic path.
CONSTITUTION: Although an exciting coil 3 is cooled by cooling water, the temperatures of a coil bobbin 4 and the outer periphery of the coil 3 rise because of a great heating value of the coil 3. However, a space 15 exists on the outside of the bobbin 4 and the outer periphery of the coil 3 and is kept in vacuum, and so only small heat is transfered from the bobbin 4 and the outer periphery of the coil 3 to an upper magnetic path 1 and a lower magnetic path 2. Specially, the space 15 between the outer periphery of the coil 3 and the inside of the magnetic path 1 is very narrow but kept in vacuum, to keep the amount of heat transfer from the outer periphery of the coil 3 to the inside of the magnetic path 1 to a minimum. It is thus possible to restrain the temperature of a sample board 10 mounted on the upper magnetic path 1 from rising and reduce drift.
| JPH0547331 | SCANNING ELECTRON MICROSCOPE |
| JP2002260574 | PARTICLE BEAM DEVICE |
| JP6400283 | Settable charged particle device |
TANAKA TAKEO
TOMITA MASAHIRO
TERAKADO SADAO
| JPS6387758U | 1988-06-08 |