Getter Pump Research Articles

Non-evaporable getter pump operations in the TCV tokamak

A non-evaporable getter pump using the ZAO alloy was installed on TCV and operated during the 2019 experimental campaign. The pump performance, determined from in-situ pumping speed measurements, indicates that current getter pump technologies are well suited to tokamak operations with high power exhaust plasmas, and provide an interesting alternative for applications in fusion experiments.

A Study of the Gettering Characteristics of Getter Pumps for Different Gases

The gettering characteristics of Ti–Zr–Al getter pumps with internal and external heaters have been measured for Н2 and CO. The results are compared to the measured similar characteristics of an NEX‑Torr D 100-05 combined pump from SAES Getters and a titanium sublimation film at temperatures of 300 and 77 K.

The Activation of Ti-Zr-V-Hf Non-Evaporable Getter Films with Open-Cell Copper Metal Foam Substrates.

Secondary electron emission (SEE) inhibition and vacuum instability are two important issues in accelerators that may induce multiple effects in accelerators, such as power loss and beam lifetime reduction. In order to mitigate SEE and maintain high vacuum simultaneously, open-cell copper metal foam (OCMF) substrates with Ti-Zr-V-Hf non-evaporable getter (NEG) coatings are first proposed, and the properties of surface morphology, surface chemistry and secondary electron yield (SEY) were analyzed for the first time. According to the experimental results tested at 25 °C, the maximum SEY () of OCMF before and after Ti-Zr-V-Hf NEG film deposition were 1.25 and 1.22, respectively. The XPS spectra indicated chemical state changes of the metal elements (Ti, Zr, V and Hf) of the Ti-Zr-V-Hf NEG films after heating, suggesting that the NEG films can be activated after heating and used as getter pumps.

Enhanced observation time of magneto-optical traps using micro-machined non-evaporable getter pumps

We show that micro-machined non-evaporable getter pumps (NEGs) can extend the time over which laser cooled atoms can be produced in a magneto-optical trap (MOT), in the absence of other vacuum pumping mechanisms. In a first study, we incorporate a silicon-glass microfabricated ultra-high vacuum (UHV) cell with silicon etched NEG cavities and alumino–silicate glass (ASG) windows and demonstrate the observation of a repeatedly-loading MOT over a 10 min period with a single laser-activated NEG. In a second study, the capacity of passive pumping with laser activated NEG materials is further investigated in a borosilicate glass-blown cuvette cell containing five NEG tablets. In this cell, the MOT remained visible for over 4 days without any external active pumping system. This MOT observation time exceeds the one obtained in the no-NEG scenario by almost five orders of magnitude. The cell scalability and potential vacuum longevity made possible with NEG materials may enable in the future the development of miniaturized cold-atom instruments.

Improvement of deuterium emission by St 172 NEG pump in a sealed off vacuum device

Zirconium based alloys are proved to be a good material for hydrogen storage as well as a vacuum pump. A non evaporable getter pump based on St 172 was tested for deuterium storage capacity in a sealed off vacuum device. The vacuum in the range of ultra high vacuum was maintained by the getter pump by gettering. Initial vacuum was created by a turbo molecular pumping system. After activation of the getter, test chamber was charged at 1 bar and 3 bar deuterium pressure for 24 h in two different experimental campaigns. After charging with deuterium, the chamber was pumped to ultimate vacuum and isolated from the TMP. The partial pressure of deuterium for different temperature of the getter was measured in sealed condition. Higher charging pressure improves the partial pressure of deuterium during desorption cycle. The experimental details and the results are presented in this article.

Adoption of getter pump for HTS superconducting cable system

For the superconducting cable operation in the real grid for over decades, one of the important technical challenges is maintaining vacuum rate of the thermal insulation cryostat vessels for avoiding system heat loss increase. When the vacuum rate is getting worse, turbo-molecular pumps etc. are usually adopted for that system. However, these pumps need to have some installation space and some electricity for the operation and moreover, periodic troublesome maintenance is needed. For the countermeasure of such issues, getter pump is selected and tested because of its smaller size, less electricity consumption and easy maintenance features. After confirming its effectivity as the vacuum pump by several investigations, this pump was employed for the termination vacuum vessel of the superconducting cable system in Yokohama. From the results of 3 weeks operation, evacuating performance exceeds turbo molecular pump and keeps vacuum state less than 1e-3 Pa stably, are confirmed respectively. This paper describes test results of the getter pump and its operation results for the real in grid system.

Reduction of waveguide vacuum trips in CEBAF accelerating cavities with a combination ion pump and non-evaporable getter pump

Pressure spikes in the fundamental power coupler waveguide are a significant source of trips during the operation of both original and refurbished superconducting radio-frequency cavities installed in the CEBAF accelerator. In its original configuration, two waveguides from a cavity-pair are connected to a single 32 l/s ion pump. In 2017 a new cavity-pair was installed in a refurbished cryomodule in which a NEXTorr®D200-5 combination ion pump and non-evaporable getter pump was installed for each waveguide. It is shown that hydrogen is the dominant residual gas in the waveguide and simulations with Molflow+ indicated that the new pumping scheme allows reducing the pressure at the end of the waveguide by a factor of ∼5, compared to the original configuration. The new cavity-pair has been operating in CEBAF for a total of 431 days and it only had a total of 3 trips due to vacuum spikes in the waveguide.

XRISE-M: X-radiography facility for solidification and diffusion studies of alloys aboard sounding rockets.

A compact fully protected microfocus X-radiography facility (XRISE-M) is presented for the study of microstructure evolution during the solidification of thin liquid alloy samples and chemical diffusion in liquid binary alloys in situ and in real-time aboard a sounding rocket. XRISE-M presently enables the simultaneous processing of either two near-isothermal solidification furnaces or a combination of a linear-shear cell diffusion furnace and a near-isothermal solidification furnace. For optimal detector calibration shortly before flight, the furnaces can be rotated around the central beam axis and calibration images can be recorded. The facility allows preheating the samples into the liquid state prior to lift-off without leakage during the ascent phase at accelerations of up to 27 g. Macrosegregation on remelting of thin metal samples for microstructure evolution investigations is prevented by an inclinable furnace metric. The use of ion-getter pumps for vacuum generation enables us to exploit the entire available time of reduced gravity for image recording and data acquisition. With the device and currently available sample environments, microstructure formation upon solidification and chemical diffusion under purely diffusive conditions in alloys can be investigated. The facility can be used equally for other investigations such as granular matter dynamics or metal foaming, provided that suitable experiment inserts are developed in the future.

Commissioning of vacuum system for SuperKEKB positron damping ring

The first stage commissioning of the new positron damping ring, which was constructed in the upgraded injector system of the SuperKEKB, was carried out from February to July 2018. Vacuum scrubbing in the arc sections, which occupy most of the ring, progressed smoothly, and a beam lifetime of 1000 s was obtained with a stored beam current of 10 mA and a beam dose of 0.7 A h. However, the beam lifetime did not increase with subsequent vacuum scrubbing because the beam lifetime was primarily determined by the Touschek effect. The residual gas composition during beam operation was typical of what would be expected for a vacuum system pumped by nonevaporable getter pumps. Rough Molflow+-based estimates of the photon-stimulated desorption yields of the beam pipe at the arc sections revealed that they decreased to 1.4 × 10−4 molec. photon−1 for H2 and to 2.3 × 10−5 molec. photon−1 for CO at a beam dose of 2 A h, which corresponds to a photon dose of 1 × 1023 photons m−1.

Response of QIT-MS to Noble Gas Isotopic Ratios in a Simulated Venus Flyby

The primary objective of the present study is to investigate the science return of future Venus atmosphere probe mission concepts using the Quadrupole Ion Trap (QIT) Mass Spectrometer (MS) Instrument (QIT-MS-I). We demonstrate the use of Monte-Carlo simulations in determining the optimal ion trapping conditions and focus the analysis on retrieving isotope ratios of noble gases in the model sample of the Venus atmosphere. Sampling takes place at a constant velocity of ~10 km/s between 112–110 km altitude and involves the use of getter pumps to remove all chemically-active species, retaining inert noble gases. The enriched sample is leaked into passively pumped vacuum chamber where it is analyzed by the QIT-MS sensor (QIT-MS-S) for 40 minutes. The simulated mass spectrum, as recorded by the QIT-MS-S, is deconvoluted using random walk algorithm to reveal relative abundances of noble gas isotopes. The required precision and accuracy of the deconvolution method is benchmarked against the a priori known model composition of the atmospheric sample.

New installation of in-vessel Non Evaporable Getter (NEG) pumps for the divertor pump in the LHD

A case of the application of Non Evaporable Getter (NEG) pumps to fusion devices is discussed. Compared with other pumping technologies used in fusion devices, the NEG pumps have advantages in terms of operation temperature at 100–200 °C (in which there is a high tolerance of the temperature increase due to a plasma radiation and/or an unexpected heat load from heating devices), low power consumption and compactness. Moreover, in the case of a power outage getters continue pumping and do not release hydrogen and its isotopes. The NEG pumps have been installed as an in-vessel pump into the divertor region in the Large Helical Device (LHD) for the first time. The pumping performance test shows that the effective pumping speed is 10 m3/s in hydrogen, which is close to the target value. In addition, the exposure of the NEG pumps to boronization and glow discharge treatments have been tested. While the boronization and glow discharge under noble gases do not show effect on the pumping performances of the NEG pumps, the establishment of an operational scenario including hydrogen and deuterium glow discharges consistent with other pumping facilities is still an aspect to be refined. However, the use of NEG pumps in LHD divertor is a milestone for the possibility of using this technology in future fusion devices.

Calibration of ultra-fine helium leak rates for leak testing of microelectromechanical systems

A novel method was developed to calibrate helium leak rates lower than 10−10 Pa m3/s. This method involves two essential points. One is the use of a leak artifact with known molecular conductance and known pressure at which molecular flow is realized. The other is that the upstream pressure of the leak artifact is determined by the static expansion method under a pressure in the range in which molecular flow is realized. In this study, a porous plug with a molecular conductance of 3.04 × 10−9 m3/s and a molecular flow realizing the pressure of 104 Pa was used as the leak artifact. The upstream helium pressure of the porous plug was determined from 133 to 10−5 Pa by repeated expansion up to five times, from which reference helium leak rates from 3 × 10−8 to 4 × 10−14 Pa m3/s were generated. The reliability of the helium leak rates so generated was examined using a cumulative helium leak detection method with a nonevaporated getter pump. The peak-to-peak data scatter including nonlinearity and repeatability was less than ±26%.

Characterization of ZAO® sintered getter material for use in fusion applications

The use of non-evaporable getter (NEG) pumps is common in many UHV applications, and the properties of the new sintered getters based on the ZAO®alloy make them appealing for applications dealing with large fluxes of hydrogen and its isotopes, as typically occurs in fusion research. In particular, the use of NEG pumps is interesting for the vacuum system of negative ion-based neutral beam injectors, which require huge deuterium gas throughputs for long durations. The key advantages of a NEG pumping solution are the high specific pumping speed and capacity, the ability to withstand a large number of absorption/desorption cycles, the ease of integration. In addition, NEG do not release hydrogen unless power is supplied to heat them, addressing an important safety issue related to uncontrolled release in case of power outage or subsystem failures.This paper reports the experimental characterization of ZAO®sintered getters, in pressure regimes and sorption amounts relevant for the use in the next generation NBI. Single discs and complete pumps were characterized in different conditions of H2/D2 pressure between 10−4 and 10-1Pa and operating temperatures up to 150°C. In particular, the feasibility of getter regeneration within time windows compatible with current NBI operation scenarios was demonstrated.

Moderne Hochkompressions‐Turbopumpen

SummaryModern high compression turbopumps – Theory and PracticeThe performance of turbopumps has shown a rapid development since their invention in the middle of the last century. Even though there are limitations due to geometry and general functionality, with the help of clever combinations of standard turbo pumps with Holweck stages, applications nowadays are possible where in the past ion getter pumps were needed. In particular modern high compression turbo pumps are suitable for generating UHV even in combination with small and simple backing pumps.

A new high precision, broad range gas micro-flow calibration apparatus

In this paper, a new calibration apparatus has been developed for gas micro-flow calibration. The apparatus employs both the constant volume method and the constant conductance method. The calibration range from 10−1 to 10−13 Pa·m3/s, and the combined standard uncertainty is 1.2%∼1.8%. When calibrating extremely low gas flow rate, the non-evaporable getter pump is used to reduce the effect of chamber wall outgassing on the measurement results, so that the lower limits of the constant volume method and constant conductance method are extended to 10−10 Pa·m3/s and 10−13 Pa·m3/s, respectively. Then a method for measurement of orifice conductance is proposed, the on-line precise measurement of the orifice conductance is realized; the consistency of flow measurement results by constant volume and constant conductance methods is better than 1.3%, then compared with the same standard leak was calibrated in both constant conductance method of the calibration apparatus and the constant pressure gas micro-flow calibration apparatus of the laboratory, and the deviation of those results was less than 1%.

Conceptual design of scalable vacuum pump to validate sintered getter technology for future NBI application

Non-evaporable getter (NEG) technology is a potential candidate as pumping system for future neutral beam injector applications. The strategy to validate the use of getter pump technology is based on the realization of a relatively large pump mock-up that has to be tested in fusion-relevant conditions. The objectives of this mock-up are to demonstrate that a pump of large dimensions and capacity is usable. This paper deals with the design of the mock-up, based on conceptual studies which involve at first 3D gas flow simulations considering different modular mock-up pumps based on NEG sintered disks. In addition transient thermal simulations with FE method have been performed with the aim to analyze the thermal response of the mock-up. The conceptual design has been carried out in order to define the best configuration to obtain high pumping speed with low spatial gradient of gas concentration inside the getter material. The suggested solution will exhibit a modular structure of getter disks, which on one hand simplifies the mechanical assembling, and on the other hand allows interpretative modelling at different scales. It is foreseen to test the pump mockup in the TIMO facility at KIT Karlsruhe.

Impact of a cryogenic baffle system on the suppression of radon-induced background in the KATRIN Pre-Spectrometer

The KATRIN experiment will determine the effective electron anti-neutrino mass with a sensitivity of 200 meV/c2 at 90% CL. The energy analysis of tritium β-decay electrons will be performed by a tandem setup of electrostatic retarding spectrometers which have to be operated at very low background levels of <10−2 counts per second. This benchmark rate can be exceeded by background processes resulting from the emanation of single 219,220Rn atoms from the inner spectrometer surface and an array of non-evaporable getter strips used as main vacuum pump. Here we report on the impact of a cryogenic technique to reduce this radon-induced background in electrostatic spectrometers. It is based on installing a liquid nitrogen cooled copper baffle in the spectrometer pump port to block the direct line of sight between the getter pump, which is the main source of 219Rn, and the sensitive flux tube volume. This cold surface traps a large fraction of emanated radon atoms in a region outside of the active flux tube, preventing background there. We outline important baffle design criteria to maximize the efficiency for the adsorption of radon atoms, describe the baffle implemented at the KATIRN Pre-Spectrometer test set-up, and report on its initial performance in suppressing radon-induced background.

Bestimmung des Saugvermögens von Ionengetterpumpen

SummaryThe pumping speed of ion getter pumps – Comparison of measurement methodsPumping speed measurements of sputtering ion pumps are typically carried out according to DIN 28429 or ISO/DIS 3556‐1.2.In this article, we take a look at the differences between these two measurement methods. Based on experimental data, the impact of pressure holding times on reproducibility and absolute values of the extracted pumping speeds are discussed.Pumping speed measurements according to the now withdrawn ISO/DIN 3556‐1.2 may yield up to 30 % higher values than values based on the validated DIN28429. The definition of sampling times according to DIN 28429 enables reproducible measurements.

Application of compact Non-Evaporable Getter and Sputter Ion Pump combination in UHV system of HIAF

HIAF-BRing, a new multi-purpose accelerator facility of the High Intensity Heavy-Ion Accelerator Facility project, requires an extremely high vacuum lower than 10−9 Pa to fulfill the requirements of radioactive beam physics and high energy density physics. Use of large speed Titanium sublimation pump (TSP) in combination with Sputter ion pumps (SIP) is not always feasible due to space limitations. A novel combination pump, based on Non Evaporable getter (NEG) and a 10 l/s SIP (NEXTorr® D 2000-10) has been evaluated as it provides large speed in a more compact design. The two combination pumps (TSP + SIP and NEXTorr D 2000-10) have been tested by dynamic flow method to measure the ultimate pressure, the pumping speed and the suitability for HIAF. Test results show that both combination pumps can be used in the pressure range of 10−10 Pa. The ultimate pressure of TSP + SIP combination pump is slightly lower than NEXTorr D 2000-10, but the latter one has much larger sorption capacities (H2: 210200 Pa l vs 265 Pa. l; CO: 430 Pa. l vs 24 Pa. l), which means it is applicable to a wider pressure range. At the same time, after twenty activation cycles, the initial pumping speed of NEXTorr D 2000-10 for H2 and CO decreased less than 10% as compared with the initial pumping speed of the first activation, which meets the actual vacuum system requirement of HIAF. A dedicated vacuum chamber with collimator and NEXTorr D 2000-10 has been designed and manufactured to stabilize the dynamic vacuum by decreasing the heavy ion induced gas desorption and increasing the gas pumping speed. The static and dynamic vacuum pressure evolution has been simulated to verify the feasibility of the NEXTorr D 2000-10 used in the HIAF-BRing.

Vacuum pumping system for the multi-aperture low-energy continuously-operated electron accelerator with a high-density beam current

The vacuum pumping system for an electron accelerator has been developed on the basis of arc sources of getter film and ion getter pumps. The contradictory problem has been solved, that is, it was necessary to provide, on the one hand, the maximum efficiency of the pumping speed and, on the other, a minimal return flow of the metallic plasma shunting the accelerating gap. The program and procedure have been elaborated for the numerical simulation of getter pumping taking into account the mass-transfer non-uniformity. The experimentally obtained vacuum characteristics of the developed pumping system for the accelerator are presented.