Penning gauge

Penmman-Zoph process Penning discharge Penning gauge Penning ionization... 

Fig. 14. Geometry of a single ceU of a penning gauge. Space charge of the trapped, circulating electrons equalizes the axis potential with that of the cathode.

The effective cross section s for ionizing collisions depends on the type of gas. According to (2.25), the discharge current i is a function of the number particle density ng, as in a Penning gauge, and it can be used as a measure of the pressure in the range from 10 to 10 mbar. At lower pressures the measurements are not reproducible due to interferences from field emission effects. 

Fig. 7.10. Cutaway of a cold cathode (Penning) gauge. The wire anode (A) is connected through a ceramic insulator (i) to the high-voltage lead (H). Under the influence of the magnetic field created by M, the elcclrons travel a long spiral path between the body and the anode. The current, which arises from electrons and positive ions of the ionized gas molecules, is related to the pressure. The open end (C) is attached to the vacuum system.

The Penning gauge in Example 5.13 is fitted with a baffle (CN2 = 2 L s 1) to reduce gauge contamination, and attached to a vacuum system. 

Fig. 14. Geometry of a single cell of a penning gauge. Space charge of the trapped, circulating electrons equalizes the axis potential with that of the cathode. Thus, the electric field is radial. Electron density is at a maximum a short distance from the anode. Electrons progress radially toward the anode only as they lose kinetic energy, mainly through inelastic (ionizing) collisions with molecules (40).

Fig. 7.49 Basic electrode layout of the Penning gauge. From Fundamentals of Vacuum Science and Technology, by G. Lewin McGraw-Hill, New York, 1965 (Fig. 5-4), reproduced with permission.

In order to measure mass losses at different inert gas pressures at constant temperature, the device was equipped with direct reading Penning gauge to control and measure the inert gas pressure quickly and accurately (better than 10 Pa). 

CVC Products, P.0. Box 1896, Rochester, NY 14603 (716-458-2550). GPH-320C Vacuum Penning Gauge with Sensor (Part 280460), 998.00 complete. 

Thermocouples, Pirani, Capacitance manometers Baratron, Penning gauges. [Mass spectrometers]... 

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