Calculation of the pumping speed of turbomolecular vacuum pumps by means of simple mechanical data

Bernhardt, Karl-Heinz

doi:10.1116/1.572058

Cited by 24 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The main 20 22 24 contributions from hydrogen, water, carbon monoxide/ nitrogen, carbon dioxide and methane are indicated. The gas composition looks similar in all three sections and is typical for an unbaked system, dominated by outgassing of the surfaces [13]. In the downstream warm section the background pressure is slightly higher, while in the cold section the contribution from hydrogen relative to water is higher because of the cold surface.…”

Section: Pressure and Gas Contentmentioning

confidence: 68%

Cold vacuum chamber for diagnostics: Analysis of the measurements at the Diamond Light Source and impedance bench measurements

Voutta

Gerstl

Casalbuoni

et al. 2016

Phys. Rev. Accel. Beams

View full text Add to dashboard Cite

The beam heat load is an important input parameter needed for the cryogenic design of superconducting insertion devices. Theoretical models taking into account the different heating mechanisms of an electron beam to a cold bore predict smaller values than the ones measured with several superconducting insertion devices installed in different electron storage rings. In order to measure and possibly understand the beam heat load to a cold bore, a cold vacuum chamber for diagnostics (COLDDIAG) has been built. COLDDIAG is equipped with temperature sensors, pressure gauges, mass spectrometers as well as retarding field analyzers which allow to measure the beam heat load, total pressure, and gas content as well as the flux of particles hitting the chamber walls. COLDDIAG was installed in a straight section of the Diamond Light Source (DLS). In a previous paper the experimental equipment as well as the installation of COLDDIAG in the DLS are described [S. Gerstl et al., Phys. Rev. ST Accel. Beams 17, 103201 (2014)]. In this paper we present an overview of all the measurements performed with COLDDIAG at the DLS and their detailed analysis, as well as impedance bench measurements of the cold beam vacuum chamber performed at the Karlsruhe Institute of Technology after removal from the DLS. Relevant conclusions for the cryogenic design of superconducting insertion devices are drawn from the obtained results

show abstract

Section: Pressure and Gas Contentmentioning

confidence: 68%

Cold vacuum chamber for diagnostics: Analysis of the measurements at the Diamond Light Source and impedance bench measurements

Voutta

Gerstl

Casalbuoni

et al. 2016

Phys. Rev. Accel. Beams

View full text Add to dashboard Cite

show abstract

“…In a mixture discharge, the gas number density of each gas depends on the mass flow rate, the pumping speed, and the conductance of the chamber, the tube, and the throttle valve [26]. To calculate the pumping speeds of oxygen and argon, the parameters of the turbo molecular pump (Turbo-V 300HT) are considered, including the blade frequency of 900 Hz, the blade outer radius of 5 cm, the solid hub radius of 2.5 cm, and the gas trapping probability about 0.98 and 1 for oxygen and argon [27], respectively. The geometries of the chamber, the connected tube, and the throttle valve are approximated as the cylinders with different radius and length [26].…”

Section: Methodsmentioning

confidence: 99%

Improvement of photoresist etching by impedance control of a bias electrode in an inductive discharge

Jiang

Jung

et al. 2023

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

To improve the photoresist (PR) etching in inductively coupled plasma (ICP) without the use of bias power, an impedance control unit is connected in series to the bias electrode of the ICP. This impedance control unit consists of an inductor and a variable capacitor to control the impedance of the bias electrode. With the series resonance of the sheath capacitance and inductance of the bias electrode impedance, the current flowing through the bias electrode increases dramatically, resulting in a higher voltage across the sheath and larger ion energy loss. The effect of series resonance on the decrease of electron density, as observed by a Langmuir probe, is illustrated by a global power balance model. As the capacitance approaches the series resonance condition, the larger ion energy leads to an enhanced PR etch rate, and the more uniform profile of the radio frequency plasma potential results in more uniform distributions of ion energy and PR etch rate. Additionally, the variation of the radio frequency plasma potential profile is attributed to the enhanced capacitive electrical field in the ICP. These variation are analysed using an electromagnetic simulation.

show abstract

“…Bernhardt 31 further says that a more precise value of the pumping speed S is obtained by integration over the ring-shaped elements along the radius from R a to R i for a constant blade angle as follows:…”

Section: Appendix A: Effective Pumping Speed Model For Tmpmentioning

confidence: 99%

Complex system reliability estimation methodology in the absence of failure data

Yadav

Choudhary

Bilen

2008

Quality & Reliability Eng

View full text Add to dashboard Cite

This paper presents a comprehensive system reliability estimation methodology for cases when failure data are unavailable, at least initially. In this methodology, the laws of physics and thermal fundamentals are used to establish a mathematical model that relates the influential input operating characteristics, such as material properties and geometry, to system performance measures. Probability distributions for each influential operating characteristic, identified from the available manufacturing data, information found in instruction manuals and related technical journals, and expert knowledge, are used to simulate the system behavior with Monte Carlo simulation. An initial reliability estimate is obtained by comparing the simulated system performance with the permissible system performance. Fuzzy logic is used to incorporate the impact of environmental factors on the performance of the simulated system performance and hence the system reliability. Finally, with the use of Bayesian analysis, initial system reliability is updated to take into account the effect of environmental factors.The proposed methodology is applied to estimate the reliability of the hazardous gas detection system used in aerospace shuttles for the timely detection of explosive gases.

show abstract

Calculation of the pumping speed of turbomolecular vacuum pumps by means of simple mechanical data

Cited by 24 publications

References 0 publications

Cold vacuum chamber for diagnostics: Analysis of the measurements at the Diamond Light Source and impedance bench measurements

Cold vacuum chamber for diagnostics: Analysis of the measurements at the Diamond Light Source and impedance bench measurements

Improvement of photoresist etching by impedance control of a bias electrode in an inductive discharge

Complex system reliability estimation methodology in the absence of failure data

Contact Info

Product

Resources

About