Getter Pump Research Articles

Construction of SuperKEKB vacuum control system and its eight years operation experience

SuperKEKB has two main rings (MRs), namely low- and high-energy rings, with circumferences of 3 km; beam transport (BT) lines; and a positron damping ring (PDR). We upgraded the MRs and BT line vacuum control systems and designed a new PDR vacuum control system for upgrading KEKB to SuperKEKB.Here, we describe the basic configuration of the vacuum control system, which includes the interlock logic (gate valve open/closed control, non-evaporable getter pump activation, and beam abortion). We subsequently present the collimator driving system and the cooling water control system for the beam pipe of the final focusing superconducting quadrupole magnet as examples of special SuperKEKB vacuum control systems. Examples of problems in the SuperKEKB vacuum control system, including the discharge at the high-voltage connector of the ion pump, stoppage of the cooling water pump for the vacuum system, and failure of the collimator position measurement device are described.

Design and implementation of intelligent control system for non-evaporable getter pumps

Abstract An intelligent control system for Non-Evaporable Getter (NEG) pumps was designed and developed. The main functions of the system include remote monitoring and remote control of key parameters of the NEG power supply, intelligent control of NEG working status according to NEG saturation status and vacuum chamber status, especially intelligent warning and protection of NEG from vacuum leaks and NEG supersaturation. The intelligent control system is proven stable and reliable, which provides a feasible logic architecture and control design for NEG pump application in future fusion devices.

Investigation on activation characterization, secondary electron yield, and surface resistance of novel quinary alloy Ti–Zr–V–Hf–Cu non-evaporable getters

The performance of next-generation particle accelerators has been adversely affected by the occurrence of electron multipacting and vacuum instabilities. Particularly, minimization of secondary electron emission (SEE) and reduction of surface resistance are two critical issues to prevent some of the phenomena such as beam instability, reduction of beam lifetime, and residual gas ionization, all of which occur as a result of these adverse effects in next-generation particle accelerators. For the first time, novel quinary alloy Ti–Zr–V–Hf–Cu non-evaporable getter (NEG) films were prepared on stainless steel substrates by using the direct current magnetron sputtering technique to reduce surface resistance and SEE yield with an efficient pumping performance. Based on the experimental findings, the surface resistance of the quinary Ti–Zr–V–Hf–Cu NEG films was established to be 6.6 × 10−7 Ω m for sample no. 1, 6.4 × 10−7 Ω m for sample no. 2, and 6.2 × 10−7 Ω m for sample no. 3. The δmax measurements recorded for Ti–Zr–V–Hf–Cu NEG films are 1.33 for sample no. 1, 1.34 for sample no. 2, and 1.35 for sample no. 3. Upon heating the Ti–Zr–V–Hf–Cu NEG film to 150 °C, the XPS spectra results indicated that there are significant changes in the chemical states of its constituent metals, Ti, Zr, V, Hf, and Cu, and these chemical state changes continued with heating at 180 °C. This implies that upon heating at 150 °C, the Ti–Zr–V–Hf–Cu NEG film becomes activated, showing that novel quinary NEG films can be effectively employed as getter pumps for generating ultra-high vacuum conditions.

First results of non-evaporable getter pump studies for the application in the EAST tokamak

Enhanced particle exhaust is pivotal in optimizing fuel recycling and bolstering plasma performance within fusion reactors. Non-Evaporable Getter (NEG) pumps, renowned for their robust high-temperature tolerance, high pumping speeds and large adsorption capabilities, emerge as highly promising candidates for augmenting the particle exhaust efficiency of tokamaks. Rigorous evaluations have been undertaken to ascertain their pumping efficacy within a vacuum testing setup and the EAST tokamak environment. Experimental data have consistently demonstrated that NEG pumps maintain stable operation across a broad temperature range, from ambient conditions to 200 °C, with a notable direct correlation observed between the pumping speed and the ambient temperature. Their performance surpasses that of conventional cryopumps, especially at D2 gas pressures exceeding 0.1 Pa. Additionally, the application of nitrogen passivation has been validated as an effective method to modulate the pumping speed and to mitigate the risk of hydrogen embrittlement and oxygen and carbon contaminations. Despite exposure to the extreme operational demands, including 30 h of plasma exposure, and lithium processing, atmospheric conditions, and water leaks, the NEG pumps preserved approximately 70 % of their initial pumping capacity. These results underscore the compatibility of NEG pumps with the challenging environments of plasma operations, positioning them as a viable and promising solution for particle exhaust in the next-generation fusion reactors.

Characterization of a NEG cartridge under high pressure conditions

The development of advanced sintered pumping elements based on the ZAO® alloy, characterized by a high affinity towards hydrogen and its isotopes, make Non Evaporable Getter (NEG) pumps particularly appealing for applications in fusion research, which typically deal with large fluxes of these gaseous species. NEG getters show high pumping speeds and capacity, excellent reliability with ability to withstand a high number of loading and unloading cycles without showing any type of failure, ease of integration within a complex system (such as a fusion reactor) because of their high specific properties and the simplicity of the mechanism that regulates its operation. These properties make NEG technology particularly suitable for the development of compact, efficient and easily scalable solutions, which are also very safe, since the release of absorbed hydrogen is prevented in the case of power outage or subsystem failures, as it can occur only by providing an adequate amount of heat to the getter material. This paper reports the results of an experimental campaign conducted on a new type of NEG pump, aimed to obtaining an accurate characterization in response to different operating conditions. Hydrogen pumping speed was investigated in a range of pressures of particular interest for the activities of the Divertor Tokamak Test facility (between 0.1 and 10 Pa). The influence of nitrogen absorption and getter material operating temperature on the pumping performances of the NEG pump were also examined. Finally, numerical simulations have been performed to estimate the nominal pumping speed of the NEG pump, that is, the one acting at the absorbing surface, stripped of the effects of the conductance of the paths from the pump NEG to the pressure gauges.

ORBITRON PUMP WITH NITROGEN CRYOPANEL

The article presents the results of a study of the operation of a vacuum orbitron getter-ion pump (OGIP) with a nitrogen cryopanel. The design features of the orbitron pump and its operating modes are described. The composition of the residual atmosphere (MX7304A mass spectrometer) of the vacuum chamber during its pumping out by the OGIP to ultrahigh vacuum has been studied. It has been established that there are no heavy hydrocarbons in the chamber, and methane is not its main component and does not determine the ultimate pressure of the pump. In an insufficiently heated vacuum chamber at Р = 2∙10-8 Pa, the main component of the residual atmosphere is water vapor. Therefore, with further thorough degassing of the vacuum chamber, the use of OGIP with a nitrogen cryopanel makes it possible to obtain an ultra-high oil-free vacuum better than 10-8 Pa.

Capacitance-based absolute pressure gauge for beamline vacuum measurement applications

For low-pressure measurements, capacitance diaphragm-based absolute pressure gauges are used owing to their high accuracy, media independence, and simplistic design. Catering to the general requirements of synchrotron beamline vacuum measurements, a capacitance diaphragm-based absolute pressure gauge is designed, developed, tested, and calibrated. The sensor is having electrode assembly which forms a dual capacitor with the gauge body. The two capacitances are used in post-processing to reduce the noise levels and to enhance the precision and accuracy of the measurements. The reference side is at high vacuum of the level 5 × 10-5 Pa. The vacuum of the reference side is generated using a Turbo Molecular Pump and is sustained by pinching-off the reference side at this vacuum. A getter pump is provided and energized for improving the vacuum which otherwise gets deteriorated due to outgassing in the reference region of the gauge. The fabrication methods adopted for fabricating the gauge are novel. The diaphragm is fabricated from bulk material using the electrical discharge method (EDM). This helped in achieving a perfect diaphragm with linear deflection with pressure variation and attained a 100% success rate. Unlike the fabrication by welding of plate, this method is robust, economical, and helped in achieving similar properties across the gauges. The second innovation is in the fabrication of electrode assembly. Unlike commonly used electrodeposited electrodes; the presented technique used copper plates which sandwich the Alumina dielectric. The plates are bolted/brazed/welded across the ceramic disc with the help of pins which also help in the parallel connection of the dual capacitors are described later. This made this method of fabrication largely rejection free with the potential of repairs and testing with different plate configurations. This paper is presenting the design, production, and calibration of the gauge using these fabrication techniques for 1 × 103 Pa to 1 × 105 Pa.

Development of non evaporable getter pumps for large hydrogen throughput and capacity in high vacuum regimes

In vacuum technology, capture pumps based on Non Evaporable Getters are commonly applied to ultra-high vacuum systems. Recent improvements in the absorption of hydrogenic species, with the introduction of Zr–V–Ti–Al alloys (ZAO®), make them an appealing and viable solution for the application in fusion research, and in particular for the vacuum system of neutral beam injectors (hydrogen pumping speed of thousands of m3/s, pressure of tens of mPa). This paper describes the characterization of the new NEG material in pumps of increasing dimensions, including the development, construction and test of a large mockup pump of modular design, to demonstrate the scalability of the technology. Effective pumping speeds of the order of 14 m3/s or higher at a concentration of 130 Pa m3/kg were achieved by the mockup pump, for an installed getter mass of about 16 kg, and a stability within 10% up to 1300 Pa m3/kg The measured effective pumping speed per unit area of sintered disks is of the order of 3.5 m/s, corresponding to 4.9 m/s at the disk surfaces as derived from numerical simulations. General guidelines for the design of large NEG pumps for hydrogen are discussed, including thermal aspects and duty cycle of the pump.

Design of a large nonevaporable getter pump for the full size ITER beam source prototype

An improvement for the vacuum system of the multidriver radio frequency (RF) prototype negative ion source SPIDER has been developed, to allow operating at high RF power, while minimizing the breakdown probability on the outside of the plasma source. A first-of-its-kind large nonevaporable getter (NEG) pump, based on a modular design of 384 cartridges totaling about 350 kg of ZAO® alloy (composed by Zr-Ti-V-Al) with an installed pumping speed at a room temperature of 330 m3/s for hydrogen, will complement the existing pumping system, based on eight cryogenic pumps and four turbomolecular pumps totaling about 90 m3/s in hydrogen. The vessel pressure during absorption is expected to be between 20 and 40 mPa, while during the getter regeneration, the peak operating pressure will be around 2 Pa. The NEG pump will use an additional vessel module, with integrated thermal shields to protect the in-vessel components during activation and regeneration of the pump, to be carried out at temperatures in the range of 550–600 °C. Integrated thermal analyses were carried out to verify the low heat load on pre-existing in-vessel components with a low limit of acceptable temperature, and to provide boundary conditions for the mechanical verifications of the pump structure. The scenario of cyclic hydrogen load was calculated considering the SPIDER operation modes, the expected gas throughput, and the cumulated load to the pump, to determine the regeneration temperature and auxiliary pumping necessary to make the regeneration duration compatible with the high availability of the system. The upgrade of the auxiliary pumping system is also described, as well as the mitigation of air or water exposure risk during regeneration of the NEG pump.

Zero-length conflat fin-type nonevaporable getter pump deposited with oxygen-free palladium/titanium

A zero-length conflat fin-type nonevaporable getter (NEG) pump deposited with oxygen-free palladium/titanium (Pd/Ti) has been developed. The NEG pump was activated by baking and its pumping speeds were measured as a function of baking time and baking temperature. The NEG pump can be fully activated by baking at 150 °C for 12 h and exhibits initial pumping speeds of 2340 L s−1 for H2, and 1440 L s−1 for CO. The initial pumping speeds of the oxygen-free Pd/Ti thin film after baking at 150 °C were estimated to be 3.2 L s−1 cm−2 for H2 and 7.6 L s−1 cm−2 for CO. The morphologies of oxygen-free Pd/Ti thin films on the partition plates and the bottom were examined by scanning electron microscopy, scanning transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The Ti thin film was completely coated with Pd on the bottom, whereas the partition plates were covered by Pd/Ti nanostructures. The present NEG pump is ideal for maintaining ultrahigh vacuum below 10−8 Pa, because its pumping speeds for H2 and CO are quite large, and because it can be fully activated by baking at 150 °C for 12 h.

Conceptual design of the Gas Injection and Vacuum System for DTT NBI

The Divertor Tokamak Test (DTT) is a new experimental facility whose construction is starting in Frascati, Rome, Italy; its main goals are improving the understanding of plasma-wall interactions and supporting the development of ITER and DEMO. DTT will be equipped with a Neutral Beam Injector (NBI) based on negative deuterium ions, designed to inject 10 MW of power to the tokamak.A fundamental system for the good operations of the DTT NBI will be its Gas injection and Vacuum System (GVS). Indeed, the efficiency of the entire NBI strongly depends on the good performance of its GVS.The GVS for DTT NBI will be composed of two systems working in parallel: a grounded section connected to the main vacuum vessel, and a high voltage part connected to the ion source vessel and working at −510 kV voltage. The grounded part will feature a fore vacuum system (given by screw and roots pumps) plus a high vacuum system based on turbo-molecular pumps located on the side walls of the vessel and Non-Evaporable Getter (NEG) pumps located inside the vessel on the upper and lower surfaces. On the other hand, the high voltage part will feature a fore vacuum system (given by two compact screw pumps mounted on the external surface for the ion source vessel) plus a high vacuum system based on turbo-molecular pumps also located on the sidewalls of the ion source vessel. A dedicated deuterium gas injection will feed the process gas to the ion source and the neutralizer.This paper gives a description of the conceptual design of the GVS for DTT NBI, and of the procedure followed to optimize this system considering the operational requirements and the other constraints of the DTT NBI.

A power-free vacuum suitcase for sample transfer and cryogenic optical characterization of sensitive 2D materials

Although some of the 2D layered materials like graphene and h-BN are stable in ambient condition, many other ones like the magnetic metal halogens CrI3 might degrade quickly in air due to oxidation or hydrolyzation that drastically affect the intrinsic properties of the pristine samples. Thus, a clean environment is highly demanded for such sensitive 2D materials during storage or transferring between synthesis and characterization setups. Additionally, variable sample temperature is crucial for characterization as well. Here, we demonstrate a specially designed vacuum suitcase that meet these challenges. It utilizes power-free non-evaporable getter pump to provide the ultra-clean vacuum environment for up to 5 samples, which could be maintained at 10−8 mbar level for 5 h and 10−7 mbar level for more 20 days. One of the samples is stored on a liquid nitrogen cooled (∼80 K–300 K) cryogenic stage, which is optimized for optical characterizations (Raman spectroscopy etc.) through a glass window. Such power-free vacuum suitcases would facilitate the clean environment sample transfer and variable temperature optical characterization of as grown sensitive 2D materials.

Study on Coated Zr-V-Cr Getter with Pore Gradient Structure for Hydrogen Masers.

As the core component of satellite navigation, the hydrogen maser needs a high vacuum environment to maintain the stability of the frequency signal. The getter pump, composed of various non-evaporable getters, plays an important role in maintaining the high vacuum. In this paper, the Zr100-xCux (x = 0, 2, 4, 6)/Zr56.97V35.85Cr7.18 getter was studied and the contradiction between sorption performance and mechanical properties was solved. The Zr-V-Cr getter, a better candidate for getter pump, exists for problems which will destroy the high vacuum and affect the service life of the hydrogen maser. To solve the problem of dropping powder from Zr-V-Cr getter, Zr-Cu films were coated on the surface of Zr-V-Cr matrix to obtain the pore gradient structure. After vacuum sintering, the interface showed gradient structure and network change in pore structure from Zr-Cu film to Zr-V-Cr matrix. These characteristic structures made Zr-V-Cr getter have good absorption properties, which is better than a similar product of SAES company and mechanical properties. Because the Zr-Cu film on Zr-V-Cr matrix effectively prevented dropping powders from the matrix, (Zr-Cu)/(Zr-V-Cr) getter solved the problem of dropping powder. The self-developed new getter with pore gradient structure is of great significance for maintaining the high vacuum of hydrogen maser in the future.

Nonevaporable getter-MEMS for generating UHV conditions in small volumina

The industrial use of quantum sensors requires further miniaturization of the experimental peripherals, i.e., the high vacuum chamber, laser technology, and control electronics. A central part of the high vacuum chamber is the maintenance of vacuum conditions. For this purpose, a prototype of a compact, i.e., miniaturized, ultrahigh vacuum pump in the form of a nonevaporable getter (NEG) pump at a wafer level (MEMS), is developed within the scope of this work. With regard to the basic conditions of the functionality of the NEG, a miniaturized heating plate with temperature sensors is analytically and numerically developed, constructed, and characterized in an ultrahigh vacuum test stand. This is followed by the integration of the NEG into the existing system, which, in connection with the characterization of material-specific parameters, enables a first correlation of heat input and pumping power. Thus, performance data of the getter-MEMS under high-vacuum confinement confirm its usability for quantum sensors. In addition, optimization potentials are shown with regard to all partial aspects of the MEMS.

Design of a vacuum system for space active hydrogen maser

With the high precision and stability of its frequency signal outputs, active hydrogen maser plays an important role in such fields as timing, satellite navigation, and communication. However, it needs to be lighter so as to be applied in space. We made a research, based on the calculation of the hydrogen flow and the adsorption efficiency of the adsorption unit, on the parameters of the vacuum system and the structural requirements, and designed a combined vacuum pump for the Space Active Hydrogen Maser (SAHM). This vacuum pump consists of a getter pump and a small ion pump, the total mass of which is about 5 kg. The pumping speed will be about 474 L/s by computation, when an amount, 2.5 MPa L, of hydrogen has been adsorbed by getters. Theoretically, the total source hydrogen inflow in lifetime is not higher than 20% of the total capacity getter pump, thus the design should amply meet the requirements of the SAHM vacuum system, and is of great significance for future SAHM applications.

Focus on software, data acquisition, and instrumentation

Focus on software, data acquisition, and instrumentation

Evaluation of Titanium Vacuum Chamber as Getter Pump

Evaluation of Titanium Vacuum Chamber as Getter Pump

Development of an EPU vacuum system using lumped NEG-ion combination pumps

A vacuum design based on five lumped ZAO® non-evaporable getter (NEG) pumps (CapaciTorr® Z 200 × 2 and NEXTorr® Z 200 × 3) was developed to construct a vacuum system of elliptically polarized undulator (EPU). The vacuum tests, including measurements of the base pressure and the sorption capacity of CO, and the pressure-rise test on turning off the ion pumps, were performed to evaluate the vacuum performance of this design. Two such EPU vacuum systems were installed in the storage ring of Taiwan Photon Source (TPS) in 2020 and were conditioned with synchrotron radiation, but without baking. The experimental results show that their dynamic pressures achieved less than 3 × 10−12 mbar mA−1 after an accumulated beam dose 100 A h.

Improved vacuum system for high-power proton beam operation of the rapid cycling synchrotron

The vacuum system in the rapid-cycling synchrotron of the Japan Proton Accelerator Research Complex has been operated for more than 10 years. It becomes evident that the high-power beam operation has more powerful effects on the vacuum system than expected at the time of the design. Those effects of the high-power beam are categorized into two types of events, the malfunction of vacuum equipment and the large pressure rise. A specific example of the former event is the failure of the turbomolecular pump (TMP) controller by the full loss of a single-shot high-intensity beam. The TMP itself is also damaged by a bearing crush due to a touch down without braking the rotor. We have developed a TMP controller that can connect with long power and control cables of more than 200 m lengths. This length makes the controller be installed in a control room where there is no radiation influence. The TMP with high-strength bearing has been also developed. The TMP system becomes tolerant to a large loss of the high-intensity beam by using such a controller and a TMP. The latter event is an extreme pressure rise with increasing the beam power. The dynamic pressure behaviors during the beam operations are investigated to understand the outgassing mechanism by the beam. It is indicated that the pressure rise mechanism is a result of the ion-stimulated gas desorption. The analytical calculation based on the ion-stimulated gas desorption model well reproduces the measured dynamic pressure. The calculation also shows that, among the parameters, a larger pumping speed per unit length $s$ and a smaller initial surface density of the adsorbed molecules ${q}_{0}$ are required to suppress the extreme pressure rise. The nonevaporable getter (NEG) pumps are additionally installed to obtain the larger $s$ and smaller ${q}_{0}$. It is confirmed by simulating the beam line pressure distribution that the additional NEG pumps are effective to obtain the larger $s$ in every position along the beam line. The ability of the NEG pump to keep a low pressure during the vacuum system shutdown, which can contribute to maintain the small ${q}_{0}$, is examined by the buildup test. It is finally confirmed that the dynamic pressure during the high-power beam is effectually suppressed.

Some Methods of Making Titanium Vacuum Chamber Act as Getter Pump for UHV/XHV

Some Methods of Making Titanium Vacuum Chamber Act as Getter Pump for UHV/XHV