Inverted magnetron manometer with enhanced operating time

If a cold-cathode ionization gauge is operated in a gas atmosphere with a high content of hydrocarbons at high pressures, the pressure reading of the gauge is disturbed by the contamination after a certain time of operation. Since in the most cases it is not possible to eliminate these disturbing residual gas components, one has to demand that the measuring process may not be substantially influenced by these gas components. To enhance the time of reliable pressure reading of a cold-cathode gauge we have equipped the entrance of an inverted magnetron gauge head with an ion baffle. By this measure the time of a reliable operation of the gauge is increased at least by a factor 3. The construction of this ion baffle is rather simple. It does not require any additional voltage supply or additional magnets. An additional feedthrough is only necessary for the measurement of the discharge current of the measuring system. The gauge has a range of pressure measurement from 10−9 to 3×10−3 mbar.