Molecular shield for an ionizaton vacuum gauge
View Patent ↗A system for measuring gas density in a vacuum includes a gauge, a housing for containing the gauge, and a magnet secured to an exterior surface of the housing. The magnet is a flexible magnetic strips, and positioned around the exterior surface of the housing. The gauge includes grid insulator posts extending longitudinally along a tubular section of the housing, and the magnet is secured to the exterior surface of the housing adjacent to the grid insulator posts, and oriented transversely to the grid insulator posts. The magnet is a flexible magnetic strip, and a clamp secures the magnet to the exterior surface of the housing.
1. A vacuum gauge comprising
an ion collector wire extending longitudinally in a tubular section of a housing,
a filament extending longitudinally along and spaced from the ion collector wire,
a grid surrounding the ion collector wire,
grid insulators extending longitudinally in the tubular section of the housing including electrical conductors for providing a voltage potential to the grid, and
a magnet disposed externally to the tubular section of the housing,
wherein the magnet is positioned over a portion of the tubular section of the housing, directly over internal grid insulator posts, and
the magnet provides a shield surrounding the grid insulator posts.
2. The vacuum gauge of claim 1 wherein
the magnet is a flexible magnetic strip, and
positioned around the exterior of the tubular section of the housing.
3. The vacuum gauge of claim 2 wherein
the magnet is secured transversely to the grid insulators on the exterior of the tubular section of the housing.
4. The vacuum gauge of claim 3 wherein
a clamp provides a press fit for the flexible magnetic strip around the exterior of the tubular section of the housing.
5. The vacuum gauge of claim 1 wherein
an interior of the tubular section of the housing surrounds a Bayard-Alpert ionization gauge, and
the magnet is a flexible magnetic strip and is fastened to surround the Bayard-Alpert ionization gauge.
6. The vacuum gauge of claim 5 wherein
the flexible magnetic strip is oriented transversely and adjacent to the grid insulators.
7. The vacuum gauge of claim 6 wherein
the flexible magnetic strip includes a plurality of magnetized strips oriented circumferentially around the exterior of the tubular section of the housing.
8. The vacuum gauge of claim 5 wherein
the magnet includes a magnetic intensity of at least 160 gauss.
9. The vacuum gauge of claim 5 wherein
the magnet is fastened to the tubular section of the housing with a stainless steel hose clamp that is adjustable to provide a press fit between the magnet and the tubular section of the housing.