BORON FLUORIDE PROPORTIONAL COUNTER

PURPOSE:To control the reaction between fluorogas and an anode filament to stabilize operation by providing the anode filament made up of nickel plated tungsten filament or nickel filament or chromium plated tungsten filament whose both ends are connected to each insulating terminal, which is tensionally streched between the insulating terminals. CONSTITUTION:Nickel plate tungsten filament or nickel tungsten or chromium plated tungsten filament is used as anode filament 9. According to this constitution, the fluorogas produced in the process of gas amplification reacts to anode filament 9 made up of a nickel plated tungsten filament to form a strong passive state film on the surface of the anode filament 9. In this case, the electric field intensity around the anode filament 9 drops as much as the portion by which the anode filament 9 become thick and the ratio of gas amplification lowers, so that gas pressure is made to slightly decrease. It is thereby possible to control the reaction of fluorogas produced by gas amplification to the anode filament and prevent the anode filament from thinning or breaking and secure a stabilized operation.