PURPOSE: To simplify the structure of the titled element to enable the drastic decrease of the weight by composing a member for supporting current introducing terminal and a vacuum measuring port of ferromagnetic materials to form a magnetic circuit.
CONSTITUTION: The measuring element is composed of electrodes 10 consisting of filament, grid and collector, current introducing terminals 11 for electrode attaching, and the current introducing terminal supporting member 13 for supporting the terminal 11 through electric insulators 12 such as ceramics. The member 13 is stuck to the vacuum measuring port 15 provided to a vacuum container wall 14, and the number 13 and the port 15 are made of magnetism shielding materials such as electromagnetic soft iron. Since the magnetic circuit is formed from the member 13 and the port 15 made of magnetism shielding material in such a way, the magnetic field near the electrode 10 is small even if outer magnetic field is impressed, the orbits of electron and ion are varied scarcely from that prior to the magnetism impression, and the sensivity is not varied substantially.
TANAKA SEI
KIMIJIMA FUMIO
ULVAC CORP