AVS 51st International Symposium
    Vacuum Technology Tuesday Sessions
       Session VT-TuP

Paper VT-TuP10
Characteristics of the Axial-symmetric Transmission Gauge on the Pressure Measurement in the Vacuum Environment including Ions and Electrons

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: N. Takahashi, ULVAC Inc., Japan
Authors: N. Takahashi, ULVAC Inc., Japan
Y. Tuzi, ULVAC Inc., Japan
I. Arakawa, Gakushuin Univ., Japan
Correspondent: Click to Email
The pressure reading of an ordinary ionization gauge is disturbed by the detection of electrons and ions generated outside of the gauge. The elimination efficiency of the axial-symmetric transmission gauge (AT gauge) for the disturbances was examined by the external sources of electrons and ions designed for this purpose. The electron source was composed of a tungsten filament and an electron collector. The ion source was made from a BA gauge from which the top electrode of the grid was removed so that ions escaped out of the ionizer. For comparison, a BA gauge and an extractor gauge were examined under the similar condition of the AT gauge. The pressure readings of BA gauge and extractor gauge showed very low pressure when the external electron source was running. In contrast, the readings of the AT gauge was not affected by the external electron source, because the ion collector is shielded by cover electrode and the retarding field for the electron is created by the end plate of the Bessel-box type energy analyzer in the AT gauge. The gas phase ions generated in the ion source of the AT gauge and ions from the external source was clearly separated in the energy spectra of AT gauge. The spectra were obtained by scanning the path energy of the analyzer of the AT gauge. The pressure measurement without the effect of ions from the outside of the gauge is made by the proper adjustment of the path energy of the analyzer. The energy analyzer in the AT gauge works as a cut off filter for the charged particles coming from the outside of the gauge as well as the original role for the rejection of the soft x-rays and ESD ions generated in the ionizer.