Turbomolecular Vacuum Pump Research Articles

CALCULATION OF THE MAIN CHARACTERISTICS OF A HYBRID VACUUM PUMP

Data are presented for calculating the main characteristics of a hybrid turbomolecular vacuum pump operating in the molecular gas flow mode. The pump contains a block of turbomolecular stages, an intermediate stage and a molecular stage with screw channels made on a cylindrical rotor. To determine the probabilities of gas molecules passing through the entire flow part of the pump in the forward and reverse directions, the Monte Carlo method in a three-dimensional formulation was used. The program allows you to evaluate the influence of the dynamic and geometric parameters of the flow path on the main characteristics of the pump in order to optimize them.

Impact of Supersonic Flow in Scintillator Detector Apertures on the Resulting Pumping Effect of the Vacuum Chambers

The article describes the combination of experimental measurements with mathematical–physics analyses in flow investigation in the chambers of the scintillator detector, which is a part of the environmental scanning electron microscope. The chambers are divided with apertures by small openings that keep the desirable pressure differences between three chambers: The specimen chamber, the differentially pumped intermediate chamber, and the scintillator chamber. There are conflicting demands on these apertures. On the one hand, the diameter of the apertures must be as big as possible so that they incur minimal losses of the passing secondary electrons. On the other hand, it is possible to magnify the apertures only to a certain extent so the rotary and turbomolecular vacuum pump can maintain the required operating pressures in separate chambers. The article describes the combination of experimental measurement using an absolute pressure sensor and mathematical physics analysis to map all the specifics of the emerging critical supersonic flow in apertures between the chambers. Based on the experiments and their tuned analyses, the most effective variant of combining the sizes of each aperture concerning different operating pressures in the detector is determined. The situation is made more difficult by the described fact that each aperture separates a different pressure gradient, so the gas flow through each aperture has its own characteristics with a different type of critical flow, and they influence each other, thereby influencing the final passage of secondary electrons detected by the scintillator and thus affecting the resulting displayed image.

OPTIMIZATION OF THE GEOMETRIC PARAMETERS OF THE MOLECULAR STAGE OF A VACUUM PUMP WITH SCREW CHANNELS ON THE ROTOR

A technique for optimizing the geometric parameters of the molecular stage of a turbo molecular vacuum pump with helical channels made on the rotor is considered. In the axial section of the rotor, the channels have a rectangular shape. As a result of numerical experiments by the Monte Carlo method in the molecular gas flow regime, the influence of each geometrical parameter of the rotor on the main pumping characteristics of the molecular stage was established. The developed program makes it possible to optimize the geometric parameters of the helical channels of the molecular stage for given overall dimensions of the rotor in order to obtain the maximum speed of action and pressure ratio.

OPTIMIZATION OF GEOMETRIC PARAMETERS OF HELICAL CHANNELS IN A MOLECULAR VACUUM PUMP

A method of optimization of geometrical parameters of a molecular stage of a turbomolecular vacuum pump with helical channels made on the stator under the molecular gas flow regime is considered. In axial section of stator the channels have rectangular shape. As a result of numerical experiments, the influence of each geometrical parameter on the main pumping characteristics of the molecular stage has been determined by the Monte-Carlo method.

Comprehensive Controller for Super Sonic Molecular Beam Gas Chromatograph Mass Spectrometer

This paper presents a new, comprehensive digital circuit used for the control of a novel gas chromatograph mass spectrometer (GC-MS) interface that is based on supersonic molecular beam (SMB). The circuit includes a Texas Instruments 150 MHz digital signal controller (DSC), high voltage amplifiers for 8 independent channels and 4 independent channels of high resolution pulse width modulation (PWM). The circuit, along with a sophisticated embedded program and a custom made personal computer (PC) application, control all aspects of the interface: smart filament emission-current stabilization, static and scanning mass-dependent ion-source voltages, transfer-line heater proportional integral differential (PID) controls with thermocouple feedbacks, on/off valves, relays and several peripheral device controls that enable the full operation of a turbo-molecular vacuum pump, and of gas flow and pressure controllers. All aspects of this comprehensive controller were successfully tested. The signal for the 450 Th ion (C32H66) for example increased by 123% which is a significant increase. It is obvious that correctly tuned dynamic voltages can guarantee the optimal signal for each mass.

CALCULATION OF GAS EMISSION FLOWS FROM THE SURFACES OF THE FLOW PART MOLECULAR STAGE OF A VACUUM PUMP

An algorithm and an example of calculation of gas emission flows from the urfaces of a molecular stage with helical channels made on the stator of a hybrid turbo molecular vacuum pump are considered. The Monte Carlo method in a three-dimensional formulation was used in calculations of the molecular regime of gas flow.

Where have all the ions gone, long time passing? Tandem quadrupole mass spectrometers with atmospheric pressure ionization sensitivity gains since the mid-1970s. A perspective.

Thegains in sensitivity since 1975 for quadrupole mass spectrometers equipped with atmospheric pressure ionization (API), and in particular triple quadrupole mass spectrometers (QqQs) since 1981, have been driven by the needs of the environmental, biomedical, agricultural, and other scientific research, industrial, regulatory, legal, and sporting communities to continually achieve lower limits of quantitation and identification. QqQs have realized a one-million-fold improvement in sensitivity attempting to address these needs over the past two score years. It is the purpose of this article to describe how that came about, not through an exhaustive review of the literature, but rather by describing what general approaches were used across the industry to improve sensitivity and provide some examples to illustrate its evolution. The majority of the gains came from the ion source and its interface to the vacuum system. "Sampling efficiency" is a measurement of the losses in this area so will be a focus of thisreview. The discovery of the phenomenon of collisional focusing was key to improving sampling efficiency because it enabled designs that increased the ion-containing gas loads from the ion source, using staged differential pumping backed by increasingly larger pumps, and prevented the scattering losses of ions in the resulting gas expansion inside vacuum. Likewise, systems with smaller pumps and lower ion-containing gas loads could be designed with size and cost reduction in mind while maintaining reasonable sampling efficiencies. As a consequence, advancements in the designs of both larger and smaller turbomolecular vacuum pumps were accelerated by pump manufacturers to accommodate the explosive growth in the use of API-QqQ and API-ion trap mass spectrometers that occurred in the 1990s and continued into the new millennium. Sampling efficiency was further improved by increasing the ion yield from electrospray by increasing the rate of droplet desolvation. An estimate of the practical limit to further sensitivity improvements beyond what has been achieved to date is provided to shed light on what to expect in the future. Lastly, the implications and unforeseen consequences of the sensitivity gains are considered with a particular focus on how they have enabled a dramatic increase in daily sample throughput on triple quadrupole and other types of mass spectrometers.

THE CALCULATION OF THE MAIN CHARACTERISTICS OF A TURBOMOLECULAR VACUUM PUMP WITH BLADES OF VARIABLE THICKNESS

The calculated dependences and the results of modeling the process of the flow of a rarefied gas through the flow part of a turbomolecular vacuum pump with blades of variable thickness in a three-dimensional formulation of the problem solution are presented. The Monte Carlo method was used for modeling. The calculations trace the movement of each gas molecule from the inlet to the outlet of the pump with the calculation of the probabilities of their passage in the forward and reverse directions. The gas flow mode is molecular.

Перспектива создания современных высоковакуумных механических насосов

High-vacuum mechanical pumps are widely used in various fields of science and technology for research and industrial applications. Modern high-vacuum mechanical pumps include molecular vacuum pumps, turbomolecular vacuum pumps and hybrid turbomolecular vacuum pumps, i.e., designs that represent a turbomolecular vacuum pump with one or more additional molecular stages. There are also a number of experimental and theoretical developments that propose combinations of different types of high-vacuum pumps in which, as a rule, on the suction side the main pumping is carried out by an axial turbomolecular stage. These schemes belong to the class of modern high-vacuum mechanical pumps. The paper examines the designs and analyzes scientific studies of modern high-vacuum mechanical pumps. Relying on this overview, we found the unsolved problems of designing and mathematical modeling of high-vacuum mechanical pumps working processes, which could give further prospects for vacuum technology development

Influence of the shape of the cross-section of the blades on the pumping characteristics of a turbomolecular vacuum pump

The influence of the shape of the cross-section of the blades of a turbomolecular vacuum pump on its main characteristics in the mode of free molecular gas flow is considered. The possibility of a significant increase in the maximum ratio of pump pressures by modifying the cross-sectional shape of rotor and stator blades is shown. Keywords: turbomolecular vacuum pump, blade cross-sectional shape, Monte Carlo method, maximum speed of action, maximum pressure ratio. fominaim@bmstu.ru

Математическое моделирование процесса течения газа в проточной части турбомолекулярного вакуумного насоса с использованием модели взаимодействия газа с поверхностью Черчиньяни-Лампис

In this paper, the process of gas flow in the flow path of a turbomolecular vacuum pump using the Cercignani-Lampis (CL) model was simulated. CL model was used as new boundary conditions when calculating the transition probability. The test particle method (Monte Carlo method) was used in the simulation. The calculation of the molecules transition probability through the blade channel in the forward and reverse directions, the transition resulting probability, the compression ratio was made.

Gas Flow in a Multistage Turbomolecular Vacuum Pump

The gas flow in a multistage turbomolecular pump is simulated so as to optimize the design of the rotor and stator blades. Monte Carlo software reveals how pump performance is affected by the geometry of the individual stages.

Numerical simulation of gas flow through the flow part of a multi-stage turbomolecular vacuum pump

The modeling of gas flow through a multi-stage flowing part of a turbomolecular vacuum pump to optimize the parameters of rotor and stator impeller wheels is considered. The developed program of statistical modeling by the Monte Carlo method allows us to determine the influence of the geometric parameters of the stages on the pump performance indicators. Keywords turbomolecular pump, impeller wheels, maximum action speed, maximum pressure ratio, Monte Carlo method. marc081939@gmail.com

Development of a calculation method of the main parameters of the multistage turbomolecular pump

We developed a calculation method of the pumping parameters of the molecular stage of the turbomolecular vacuum pump (TMP) operating in the molecular flow region. Also, the authors developed the calculation method of the main parameters of the multistage TMP for the providing the main pumping parameters including ultimate pressure, pumping speed, compression ratio. As a result of calculation, the we got the performance curve of the multistage TMP.

The Nixie tube story

ON A COLD DECEMBER MORNING in the Czech village of Brezolupy, a man stops his truck in front of a 17thcentury castle. He puts on some heavy gloves, steps out of the truck, and opens the back hatch. Carefully, almost lovingly, he unloads crate after crate of heavy equipment and supplies-an industrial glass lathe, a turbomolecular vacuum pump, and glass. Lots and lots of glass.

Методика расчёта откачной характеристики высоковакуумной системы с турбомолекулярным вакуумным насосом

Методика расчёта откачной характеристики высоковакуумной системы с турбомолекулярным вакуумным насосом

Определение эффективного диапазона давлений газа на стороне всасывания турбомолекулярного вакуумного насоса

Определение эффективного диапазона давлений газа на стороне всасывания турбомолекулярного вакуумного насоса

Определение оптимальных параметров проточной части турбомолекулярного вакуумного насоса

Определение оптимальных параметров проточной части турбомолекулярного вакуумного насоса

Experimental and performance analyses of a turbomolecular pump rotor system

This study focuses on the experimental and performance analyses of a vertical turbomolecular vacuum pump (TMVP) rotor system. This approach can adopt various methods, such as numerical parametric analyses and experimental measurements. The analysis process can verify the finite element models of the rotor system under different boundary conditions by using pump system assembly testing data. Afterward, the dynamics characteristics of the rotor system must be calculated and compared with the experimental results to verify the models. Finally, the relationship between rotor critical speed and bearing stiffness can be established to study the design of the TMVP rotor system. The experimental analysis can adopt static modal and dynamic testing. Static modal testing can provide the natural frequencies of the rotor system. The waterfall diagram of dynamic testing can measure the operating critical speed of the vacuum pump system from 0 rpm to the operating speed and ensure that the operating speed is far from the critical speed or at least within 10% of the safe margin. In summary, results of the experimental testing and numerical parametric analysis can provide the basis for the design tool of the TMVP rotor system to identify and prevent vacuum pump vibrations.

Перспективы развития комбинированных турбомолекулярных вакуумных насосов

Перспективы развития комбинированных турбомолекулярных вакуумных насосов