A review on hot cathode ionisation gauges with focus on a suitable design for measurement accuracy and stability

project 16NRM05 'Ion gauge'A literature review starting from 1950 is given on the design and geometry of ionisation gauge types with hot cathodes. Considerations on the material of the electrodes and of surface effects are included. The review focuses on the design issues for measurement accuracy, linearity, repeatability, reproducibility, and stability of sensitivity. Also, the attempts to reduce the lower measurement limit are reviewed to some extent.publishersversionpublishe

Evaluation and metrological performance of a novel ionisation vacuum gauge suitable as reference standard

Funding Information: This work has received funding from the EMPIR programme (projects 16NRM05 and 20SIP01) co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme and the Portuguese National Funding Agency for Science, Research and Technology in the framework of the project UIDB/FIS/ 00068/2020. Publisher Copyright: © 2023 The Author(s)Recently, a new type of ionization vacuum gauge was introduced, which was proposed as a reference and transfer standard in the range of 10-6 Pa to 10-2 Pa because of its excellent stability and linearity. In contrast to present models of ionisation vacuum gauges, all electrons have a well-defined path length through the ionisation space. This even allows one to predict the sensitivity for a gas species provided that the ionisation cross section of the gas molecules for electrons between 50 eV and 200 eV is known. Following the development of this gauge we investigated its metrological performance in terms of linearity, resolution, repeatability, reproducibility, transport and long-term stability, disturbances by magnetic fields, influence of the surrounding earth potential and so on. The gauge demonstrated excellent metrological properties and is indeed suitable as an accurate reference and transfer standard, but can also provide important economic benefits to manufacturers and users.publishersversionpublishe

Development of a design for an ionisation vacuum gauge suitable as a reference standard

UID/FIS/00068/2019The EURAMET EMPIR project “16NRM05 - Ion gauge” aims to develop an ionisation vacuum gauge suitable as a reference vacuum standard. In such a gauge the electron trajectories and their kinetic energy inside the ionisation volume should be well defined and stable. In the search for a suitable design, a series of simulations on different ionisation gauge concepts that have the potential to meet stringent stability requirements have been carried out. Different software packages were used for this purpose. This paper focuses on the design aspects and the performance of the different ionisation gauge concepts that have been investigated by simulation. Parameters such as ionisation gauge sensitivity, ion collection efficiency and electron transmission efficiency, have been determined as a function of emission current, pressure and electron source alignment.publishersversionpublishe

Grundwasser - Altlasten - Boden aktuell

Neun Fachbeiträge dokumentieren Ergebnisse der aktuellen Projekt- und Forschungsarbeit des Landesamtes in den Themenbereichen Grundwasser, Altlasten und Boden. Die Inhalte reichen vom Interesse aus Namibia für diese Themenbereiche über verschiedene Auswertungen von Hintergrundwerten und Hochwasser 2013 bis hin zu Planungen im Bereich Bodendauerbeobachtung in Sachsen. Einzelerkenntnisse zu Wülknitz bzw. zum Tagebau Witznitz werden in dem Heft fortgeführt

Grundwasser - Altlasten - Boden aktuell

Neun Fachbeiträge dokumentieren die Ergebnisse der aktuellen Projekt- und Forschungsarbeit des Landesamtes in den Themenbereichen Grundwasser, Altlasten und Boden

Electrons on a straight path : ǂa ǂnovel ionisation vacuum gauge suitable as reference standard

The consortium of the European project 16NRM05 designed a novel ionisation vacuum gauge in which the electrons take a straight path from the emitting cathode through the ionisation space into a Faraday cup. Compared to existing ionisation vacuum gauges, this has the advantage that the electron path length is well defined. It is independent of the point and angle of emission and is not affected by space charge around the collector. In addition, the electrons do not hit the anode where they can be reflected, generate secondary electrons or cause desorption of neutrals or ions. This design was chosen in order to develop a more stable ionisation vacuum gauge suitable as reference standard in the range of 10−6 Pa to 10−2 Pa for calibration purposes of other vacuum gauges and quadrupole mass spectrometers. Prototype gauges were produced by two different manufacturers and showed predictable sensitivities with a very small spread (&lt;1.5%), very good short-term repeatability (&lt;0.05%) and reproducibility (&lt;1%), even after changing the emission cathode and drop-down tests. These characteristics make the gauge also attractive for industrial applications, because a gauge exchange does not require calibration or re-adjustment of a process. •A novel ionisatiThe consortium of the European project 16NRM05 designed a novel ionisation vacuum gauge in which the electrons take a straight path from the emitting cathode through the ionisation space into a Faraday cup. Compared to existing ionisation vacuum gauges, this has the advantage that the electron path length is well defined. It is independent of the point and angle of emission and is not affected by space charge around the collector. In addition, the electrons do not hit the anode where they can be reflected, generate secondary electrons or cause desorption of neutrals or ions. This design was chosen in order to develop a more stable ionisation vacuum gauge suitable as reference standard in the range of 10 −6  Pa to 10 −2  Pa for calibration purposes of other vacuum gauges and quadrupole mass spectrometers. Prototype gauges were produced by two different manufacturers and showed predictable sensitivities with a very small spread (<1.5%), very good short-term repeatability (<0.05%) and reproducibility (<1%), even after changing the emission cathode and drop-down tests. These characteristics make the gauge also attractive for industrial applications, because a gauge exchange does not require calibration or re-adjustment of a process.The consortium of the European project 16NRM05 designed a novel ionisation vacuum gauge in which the electrons take a straight path from the emitting cathode through the ionisation space into a Faraday cup. Compared to existing ionisation vacuum gauges, this has the advantage that the electron path length is well defined. It is independent of the point and angle of emission and is not affected by space charge around the collector. In addition, the electrons do not hit the anode where they can be reflected, generate secondary electrons or cause desorption of neutrals or ions. This design was chosen in order to develop a more stable ionisation vacuum gauge suitable as reference standard in the range of 10-6 Pa to 10-2 Pa for calibration purposes of other vacuum gauges and quadrupole mass spectrometers. Prototype gauges were produced by two different manufacturers and showed predictable sensitivities with a very small spread (< 1.5%), very good short-term repeatability (< 0.05%) and reproducibility (< 1%), even after changing the emission cathode and drop-down tests. These characteristics make the gauge also attractive for industrial applications, because a gauge exchange does not require calibration or re-adjustment of a process

Novel ionisation vacuum gauge suitable as a reference standard : influence of primary electron trajectories on the operation

A detailed study of the operation of a novel ionisation gauge, recently proposed as a reference standard by the consortium of the European project 16NRM05, is performed with focus on the influence of electron trajectories and the interaction of electrons with electrode surfaces. The strategy behind the gauge design was to provide well defined primary electron trajectories that form an electron beam. This investigation seeks to correlate experimental investigations of improper primary beam focusing, electron beam profiling, electron stimulated desorption and outgassing, with charged particle optics simulations that include space charge effects, and a detailed study of secondary electron emission. The main outcome of the research is that control of the primary electron trajectories, quantified by electron transmission efficiency, is essential for its proper operation mainly as a pressure measurement device but also as a vacuum gauge sensitivity reference standard. Once all primary electrons end their trajectories in a Faraday cup, being one of the gauge electrodes, two additional problems are identified: escape of a very small fraction of electrons from the Faraday cup and electron stimulated desorption of neutrals. Their contribution is of low significance when using this device as a sensitivity reference standard in the high vacuum range, which meets the major goal of the 16NRM05 project. However, these effects might represent an obstacle for the gauge application, mainly as a measurement device, at lower pressures. Approaches to mitigate the mentioned potential problems are discussed