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Penning gauge. A type of cold-cathode ionization gauge in which a discharge is maintained between two electrodes with a potential difference of a few kilovolts. An axial magnetic field is also applied to cause electrons to move in spiral paths and increase the ionization current and sensitivity. This type of gauge is used in the range 10−3− ...
- Abstract
- 1 Introduction
- 3.1 The Penning gauge
- 5 Comparison of crossed field (CFG) and emitting cathode (ECG) ionization gauges
- 6 Problems in applications of ionization gauges
- General reasons for measurement uncertainties
- Gauge-specific reasons for measurement uncertainties
Ionization gauges exclusively are used for ultrahigh vacuum. After a brief history, the design, use, and accuracy of ionization gauges will be described in this article.
In the ultrahigh vacuum (UHV) regime it is not possible to measure pressure as a force on a certain area as the definition of pressure indicates. Instead, it turns out that the only practical and economically reasonable indicator for pressure in UHV is the ionization rate produced by electrons hitting the neutral gas atoms in a UHV chamber (Fig. 1)...
The working principle of this type of gauge is to generate a discharge between two metal electrodes (anode and cathode) by applying a DC high voltage. The discharge current is pressure dependent and serves as measurand for pressure. The lower measurement limit lies around 1 Pa, since at lower pressures the gas density is too low to generate enough ...
As a summary, the major types of ionization gauges have been schematically drawn by Redhead (Fig. 19). CFGs have the general advantage that they have no X-ray limit (the electron current producing X-rays is proportional to pressure) and electron stimulated desorption effects are small and cause few errors. Also, because they already have a strong m...
Special to the application of ion gauges in accelerators are their interaction with radiation, strong magnetic fields, and EM radiation mainly in the radiofrequency range: radiation capable of ionizing molecules may contribute inside the gauge head to the ion current. Miertusova [36] found completely erratic pressure indications when an inverted ma...
Uncertainties due to calibration chain Uncertainties due to installation (or mistakes in installation) Uncertainties due to operation (surface layers, corrosion, dust, ageing) Inaccuracies caused by gas mixture Uncertainties caused by the device itself Table 6: Uncertainties that are caused by the individual ionization gauge
Offset due to X-ray, ESD, electronics, incomplete insulation Offset instability (drift) Resolution Influences of environment (mainly temperature) Non-linearity Integration time (scatter of data), repeatibility Reproducibility (stability of calibration constant) Hysteresis (ESD) Prior usage, cleanliness The calibration constant of an emitting catho...
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- K Jousten
- 24
- 2007
Feb 14, 2019 · The Penning gauge is the style most often used in vacuum furnaces. Hot cathode ionization gauges can also be used and will be the subject of a future discussion. Ionization gauges are relatively accurate at high vacuum and are an indirect-acting type of gauge.
- VAC AERO International
PENNINGVAC PTR 225 RN: Pure cold cathode. Our cold cathode gauges use the PENNING principle of cold cathode ionization. Their measuring range of 10 -2 to 10 -9 enables you to measure into the high vacuum region. To control the turning on of the gauge, it would be best combined with one of our THERMOVAC or CERAVAC gauges.
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The Penning cold cathode gauge provided a robust alternative to the hot filament or Bayard-Alpert gauge. Its discharge, however, would extinguish when used at vacuum levels below 10 -7 Torr. This is a problem that would be solved years later but fostered the proliferation of Bayard-Alpert sensors, which had none of these measurement limitations.
The ion current that is collected by the negatively biased collector can be related to pressure once the gauge has been calibrated. The basic gauge equation for ionization gauges is: IC = KnIe. where Ic is the ion current, K is a constant relating to the ionization probability, n is the number density of gas molecules and Ie is the ionizing ...
