Penning vacuum meter

A penning vacuum meter that includes:

• a cathode housing having a flange at one end for connecting the housing to a vacuum chamber and an opening passing axially through said housing;
• a U-shaped cathode, mounted in said housing, said cathode having two opposed rectangular shaped arms connected by a flat base plate, said arms being parallel to the axis of said housing and being tightly fitted against opposed inner walls of said opening with the base plate of the cathode passing across the opening at the flange;
• an annular shaped anode suspended within said opening between the arms of said cathode, said anode lying in a plane that is parallel with said arms, the diameter of the anode being substantially equal to the width of said arms;
• and
• said cathode being formed of a material that will resist disintegration when bombarded by accelerated ions when operating within a pressure range of between 10−4 and 10−2 mbars.