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Volume 37, Issue 9
Displaying 1-23 of 23 articles from this issue
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Charles R. TILFORD1994 Volume 37 Issue 9 Pages 667-672
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSThe measurement of partial pressures in the ultra high and extreme high vacuum ranges (below about 10-6 Pa) is important for residual gas analysis and the measurement of low-pressure constituents (both contaminants and deliberate additions) in higher-pressure process gases. Mass-spectrometer type instruments-partial pressure or residual gas analyzers (PPAs and RGAs) -are generally used for this purpose. Typically, these instruments consist of an electron-impact ionizer, a quadrupole mass filter, and an ion detector. This paper discusses these elements and other factors that determine the very-low-pressure performance of these instruments-detection limits, mass resolution, and stability and pressure-dependence of the sensitivity. Particular attention is paid to ion-source design and operating parameters, the coupling of ions between the ionizer and the mass analyzer, and the influence of the total pressure on partial pressure sensitivities.View full abstractDownload PDF (948K) -
Chuhei OSHIMA, Astushi YOSHIMI, Tomohiko SATOH, Masahiro TAKIZAWA1994 Volume 37 Issue 9 Pages 673-677
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSThe time-of-flight (ToF) measurement together with the energy analysis provides us with information concerning the ionization area inside a grid. An ionization gauge with a large-angle deflector has been used to measure a sequence of ToF spectra as a function of the ion energy in 6×10-10 Pa. These data suggest that the ionization area inside the grid is restricted to a narrow region owing to the focusing of the electron beam.View full abstractDownload PDF (647K) -
Karl JOUSTEN1994 Volume 37 Issue 9 Pages 678-685
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSWhen total pressures decrease to the XHV region, measurements with ionization gauges become increasingly sensitive to disturbances such as electron- or photonstimulated desorption, outgassing of the gauges, and production of secondary electrons by X-rays. Therefore, it is very important to have a reliable pressure scale also in the XHV region. The laboratory for vacuum physics at the Physikalisch-Tech-nische Bundesanstalt (PTB) in Germany provides a calibration system with molecular beam expansion for pressures down to 10-10 Pa and is building a new calibration system based on continuous expansion for a lower calibration limit in the 10-11 Pa decade. The advantages and disadvantages of the two systems will be discussed and calibrations with the molecular beam system will be presented. For determining the outgassing rate of the vacuum chamber of the new calibration system, a new method was applied and compared to the classical methods, the throughput method and the pressure rise method. In particular it was checked whether the outgassing rate depends on the pumping speed applied to the chamber as proposed in a theory by Malev.View full abstractDownload PDF (954K) -
Christian EDELMANN, Thomas IWERT, Ralf KAUERT, Wolfram KNAPP, Falk MER ...1994 Volume 37 Issue 9 Pages 686-691
Published: September 20, 1994
Released on J-STAGE: January 28, 2010
JOURNAL FREE ACCESSAn axial emission ionization gauge with an electrode construction similar to that of J. Z. Chen and C. D. Suen (An axial-emission ultrahigh vacuum gauge. J. Vac. Sci. & Technol. 20 (1), 88-91 (1982)) was studied experimentally with respect to its applicability as a calibration gauge for use in the UHV range. The optimum operation parameters were determined experimentally. At these values of the operation parameters the sensitivity is smaller than that in the publication of Chen and Suen. In contrast with the ionization gauge of the extractor type, the sensitivity of the modified axial emission gauge depends only very weakly on the electron current and pressure, so that its application as calibration gauge in the UHV region seems possible from this point of view. In the low-pressure region, the influence of gas exposure on the pressure reading was studied for a gauge with a molybdenum anode and one with a platinum anode. In both cases the electron-stimulated desorption (ESD) caused errors in the pressure reading. If a platinum anode was used, the influence of hydrogen was larger than that of oxygen. In the case of a molybdenum anode, the influence of oxygen was larger than that of hydrogen. This behavior is accounted for by the greater adsorption of hydrogen on platinum. The experiments on the ESD demonstrate that the axial emission gauge has a somewhat lower collection efficiency for ESD ions generated on the anode surface than for those generated by electron impact in the space surrounded by the grid. This is in conformity with some calculations of ion trajectories performed with the program SIMION.View full abstractDownload PDF (713K) -
Toru KANAJI, Shizuo NAKAMURA, Toshio URANO, Shozo HONGO1994 Volume 37 Issue 9 Pages 692-695
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSThe operation of a “cascade static lens gauge” (CSLG) was studied in a new extremely high-vacuum system. In the gauge, electrons emitted from a hot cathode oscillate many times in a lens system which is installed between the cathode and an ion collector. The potentials of the lens electrodes, which were apertured disks, were determined by computer simulation and from preliminary experiments. The sensitivity of about 90 Pa-1 was obtained with an emission current of 0.55 μA. The linearity was confirmed in the measured pressure region. Soft X-ray photocurrent and ESD ion current were below our detection limit due to the small emission current, but the low-pressure measurement in the extremely high vacuum was not easy because outgassing from the lens electrodes could not be neglected in spite of the small emission current.View full abstractDownload PDF (507K) -
Toru KANAJI, Shizuo NAKAMURA, Toshio URANO, Shozo HONGO1994 Volume 37 Issue 9 Pages 696-699
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSThe cascade static lens gauge (CSLG) has a lens system in which electrons oscillate many times, generating ions with a high probability. In a preliminary work using a prototype (CSLG-1), a sensitivity higher than 80 Pa-1 was obtained with emission current of 0.55μA. In the experiments in XHV, however, the effects of outgassing from the working electrodes were not negligible, and the design of a new gauge (CSLG-2) was started. In the new gauge, the lens system is composed of ring electrodes installed in line instead of the apertured disks used in CSLG-1, and the rings can be heated by passing an electric current through them directly or by electron bombardment. In the computer simulation study, the electron stably oscillates more than 10000 times, and high performance is expected.View full abstractDownload PDF (453K) -
C. D. Suen, Y. D. Zheng, B. D. Xu1994 Volume 37 Issue 9 Pages 700-702
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSOn the basis of the axial-emission ionization gauge (AEG) and the oscillator mini-ion gauge (OMG), a mini-axial-emission ionization gauge (MAEG) with a needle collector and a small ring anode has been developed. Due to the confinement of the electrostatic saddle field around the anode ring, its sensitivity is high (3.9 Pa-1) and the X-ray limit is low the lower limiting pressure is about 1.2×10-10 Pa at Ie=100μA, Va=1000V, Vk=50V, Vs1=Vs2=0 and Vc=0.
Its small size and simple electrode construction than AEG makes degassing unnecessary, and its filament works at a lower temperature. All these make the MAEG more suitable for UHV measurement and even for XHV measurement. Furthermore, the upper limit of the MAEG can be extended to 6.7×10-2 Pa when Ie is decreased to 10μA and Vs1=50V.View full abstractDownload PDF (266K) -
J. Patrick LOONEY1994 Volume 37 Issue 9 Pages 703-710
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSFor some time, laser photoionization has been used to detect low concentrations of atoms, molecules, and radical intermediates in a variety of applications, including analytical chemistry, combustion, plasma and CVD diagnostics. Several of these studies have shown that laser photoionization has the fundamental sensitivity and selectivity necessary for species-specific partial pressure measurement in the ultrahigh vacuum regime. This body of work has, in part, spurred interest in the application of laser photoionization to measurements of pressures in the UHV regime. In this paper we discuss the results of the recent research conducted at NIST on the use of laser photoionization for quantitative pressure measurements and the factors which limit the pressure measurements based upon this technique.View full abstractDownload PDF (884K) -
Kiyohide KOKUBUN, Shigeyuki SEKINE, Shingo ICHIMURA, Akira KUROKAWA, H ...1994 Volume 37 Issue 9 Pages 711-713
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSBy means of nonresonant multiphoton ionization using a picosecond pulsed YAG laser, pressure measurement for H2, CO and CO2 gases was carried out in the XHV pressure range. It was experimentally verified that pressure measurement was possible in the range of 10-11 Pa, and this pressure measurement method had pressure sensitivity of the same order of magnitude for the three molecules.View full abstractDownload PDF (412K) -
Shigeyuki SEKINE, Kiyohide KOKUBUN, Shingo ICHIMURA, Hazime SHIMIZU1994 Volume 37 Issue 9 Pages 714-717
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSThe measurement of gas pressure in ultrahigh vacuum was carried out by detecting laser-generated photoelectrons. Xenon atoms filling a vacuum chamber were nonresonantly ionized by a picosecond laser pulse. The laser intensity dependence of the number of ions produced was measured, and almost all xenon atoms in a focal area were found to be ionized. The number of photoelectrons produced was also measured as a function of xenon pressure. The signal intensity was proportional to xenon pressure in the range from 10-2 to 10-7 Pa.View full abstractDownload PDF (476K) -
Johan K. FREMEREY1994 Volume 37 Issue 9 Pages 718-722
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSA major concern in the XHV technique is hydrogen outgassing from the vacuum container walls. It will be demonstrated in the present paper that residual gas accumulation under sealed-off conditions and monitoring the pressure rate by a spinning rotor gauge (SRG) is a simple and adequate method for the determination of extremely low outgassing rates. Q, Opening of the pump valve will cause the system pressure, P, to settle according to the effective pumping speed, S, by the simple relation P= Q/ S. For practical reasons, we use Q= V (dP / dt) 0, with V denoting the system volume, so that P= (dP/ dt) 0τp, where τp= V/ S is the pump-down time constant, and (dP/ dt) 0 is the pressure rate inside the sealed system, i.e., with the pump valve shut off. By using a standard commercial SRG unit, systems can be qualified at the 100 pPa (10-12 mbar) level. No pumping or contamination occurs to the system as with conventional ion gauges.View full abstractDownload PDF (615K) -
Tatsuo IWATA, Kap-Soon CHANG1994 Volume 37 Issue 9 Pages 723-726
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSOutgassing rate upon electron impact from the phosphor screen of a field emission microscope has been measured as a function of anode current and applied voltage. The outgassing rate increased quickly with anode voltage up to about 1.5 kV; after that it increased only slightly. At the practical anode voltage used in field emission experiments, the outgassing rate substantially depended on only emission current and was found to be 3×10-1 Ie (Pa·m3/s·m2). From this relationship, we conclude that if we use a In A or lower emission current there are few effects on the reading of pressure with a field emission vacuum gauge in UHV, and in XHV as well.View full abstractDownload PDF (513K) -
Minsheng XU, Yutaka MATSUI1994 Volume 37 Issue 9 Pages 727-731
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSIn order to obtain a clean extremely high vacuum, we made use of copper ultrafine powder (Cu UFP) as cryosorbent in bakeable-type cryopumps. Cu UFP was sintered on cryopanels and was cooled to temperatures less than 20 K to adsorb hydrogen. With use of the cryopumps, their cryopanels could be heated to the temperature of 200°C, which is effective for desorption of water from Cu UFP during regeneration. From studies on the pumping characteristics as a function of temperature, we found that the Cu UFP cryopanel at temperatures <20 K has sufficient pumping capacity for hydrogen released from a well-baked vacuum chamber. After successive bakeouts during regeneration and cryopumping, the test dome was evacuated to a pressure <10-10 Pa which was maintained for several weeks.View full abstractDownload PDF (683K) -
Hiroyuki KINPARA, Kazutoshi HIRASAWA, Tsuyoshi KOTANI, Masaaki NISHIYA ...1994 Volume 37 Issue 9 Pages 732-735
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSWe have developed a sputter ion pump (SIP) to obtain a lower ultimate pressure.The pressure of a test chamber was reduced to 6.8×10-10 Pa by the SIP after 250°C bakeout for 48 hours. The pump is able to start the discharge in 1.41.8 min after turning on the power supply at 1.61.9×10-9 Pa, and in about 10 s at 14×10-8Pa. The achievement of the extremely high-vacuum, XHV, and the easy discharge initiation indicate that the Penning discharge is still strongly maintained at the very low pressure.View full abstractDownload PDF (671K) -
Tatsunori KOIZUMI, Yoshitaka HAYASHI, Hisashi HORIUCHI1994 Volume 37 Issue 9 Pages 736-741
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSIn order to develop a sputter ion pump (SIP) which works effectively in the pressure range lower than 10-10 Pa, two types of a 400 L/s SIP, triode type and post type, have been evaluated, and are used in combination with the Zr-V-Fe nonevaporable getter (NEG) module. Activation of the NEG module has been achieved during the bakeout of SIP by a plate heater placed on the outer surface of the SIP body. In the case of post-type SIP with the NEG module, the ultimate pressure of 6×10-11 Pa has been obtained in 1, 000 h from atmospheric pressure with a total of about 24 h of bakeout at 280°C for SIP and the test dome, and at 290°C for activation of the NEG module. Also, Ar conditioning of SIP has been attempted to reduce the ultimate pressure.View full abstractDownload PDF (718K) -
Masashi IGUCHI, Masatomo OKAMOTO, Tadashi SAWADA1994 Volume 37 Issue 9 Pages 742-750
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSThe ultimate pressure of a turbomolecular pump (TMP) depends on its backing pressure and compression ratio. Performance of TMP was analyzed, taking the out-gassing from TMP blades into consideration. A 250 L/s TMP and a 1100 L/s compound molecular pump (CMP) were designed based upon this theory and their performance was measured. The ultimate pressure was 5E-10 Pa, which is in the XHV region.View full abstractDownload PDF (986K) -
Y. C. LIU, J. R. CHEN, G. Y. HSIUNG, J. R. HUANG1994 Volume 37 Issue 9 Pages 751-757
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSThe SRRC 1.3 GeV electron storage ring was designed as a third-generation synchrotron light source. Aluminum alloys were adopted as the materials of the ring vacuum chambers. The anti-chamber structure with a “concentrated + distributed ion pump” pumping configuration effectively removed the desorbed gas molecules in the bending chamber. A computer program was devised to simulate the distribution of the outgassing rate in the storage ring. It was shown that the arrangement of the pumps, according to the simulation, was effective to reduce the average pressure. An oil-free machining method with complete oil-free pumping configuration resulted in the reduction of the hydrocarbon contamination on the surface of the chamber. The welding and installation work were performed in a clean room or dust-controlled area so that little dust trapping was observed during the machine operation. The desorbed gases were mainly hydrogen molecules, which had less effect on the beam lifetime. An accumulated beam dose of>80 A·h was quickly achieved and the pressure rise per electron beam current (dP/dI) was reduced by three orders of magnitude in a short time period of normal operation.View full abstractDownload PDF (671K) -
Kenji ODAKA, Kazue TAKAHASHI, Shinjiro UEDA1994 Volume 37 Issue 9 Pages 758-762
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSSpecimen transportation into extremely high vacuum was investigated using a system consisting of three chambers manufactured from type 304 stainless steel. The main chamber was evacuated with a turbomolecular pump and a titanium sublimation pump with a shroud at room temperature. Transport from the entry chamber at atmospheric pressure to the main chamber at 7×10-10 Pa through a preparation chamber at 2×10-8 Pa took four hours. Pressure recovery after transport took 30 minutes in the 10-10 Pa range. Residual gas analysis showed that this recovery time might be attributed to slow desorption of the water adsorbed on the main chamber surface during transport. On the other hand, the hydrogen, methane, carbon monoxide and carbon dioxide pressures reached the background level within a few minutes after transport was completed. It was also found that as much methane and carbon oxides as hydrogen were released from the equipment during transport.View full abstractDownload PDF (597K) -
Katsumi WATANABE, Shizuo NAKAMURA, Akihiro TANAKA, Masami TAGUCHI, Ret ...1994 Volume 37 Issue 9 Pages 763-767
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSFor almost the past two decades, surface analysis instruments have maintained an UHV environment which is achieved by UHV pumps. Recently, the XHV environment has been required in surface analysis, but an instrument which has many parts in a vacuum is eventually limited in the baking temperature. To achieve an XHV environment in a surface analysis instrument, H2 is the key component. Thus we tested a nonevaporable getter pump to reduce the amount of H2 and we have measured the residual mass spectrum in a practical instrument using a low outgassing rate mass spectrometer. We obtained a low range of 10-9 Pa using the NEG pump and conventional pumps with relatively low baking temperature. The ion source of the sputter-etching gun was mainly the outgassing of H2 under operating conditions, and hence the pumping speed was not sufficient to maintain the amount of H2 from the ion gun.View full abstractDownload PDF (492K) -
Michio MINATO, Yoshio ITOH1994 Volume 37 Issue 9 Pages 768-771
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSTitanium is a promising candidate material for vacuum chambers for UHV (ultra high vacuum) and XHV (extreme high vacuum) applications. It has such advantages as light weight, high corrosion resistivity and great mechanical strength. We have studied the outgassing rates of small samples of stainless steel and titanium after various surface treatments. Titanium was found to have a lower outgassing rate, and the surface treatment of coating TiN is effective to reduce the outgassing rate. Taking these advantages into consideration, we configured a vacuum chamber made of TiN-coated titanium and obtained an ultimate pressure of 5.8×10-11 Pa in XHV region. Mass analyses of gases from small samples were studied and discussed.View full abstractDownload PDF (504K) -
Chuhei OSHIMA, Noriaki ARAI, Katsumi NAGAOKA, Hiroyuki OGAWA, Manabu Y ...1994 Volume 37 Issue 9 Pages 772-775
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSA new apparatus for high-resolution field emission spectroscopy has been developed by combining the two techniques of extremely high vacuum and high-energy-resolution electron spectroscopy. The base pressure of the constructed vacuum sys tem was 10-10 Pa, and the pressures of 10-9 Pa were maintained in the field emission experient. The high energy resolution of 1 meV was attained with three stages of cylindrical electrostatic analyzers. The typical energy distribution of the field emission from a tungsten (111) tip at room temperature obtained with the apparatus agreed with the theoretical curves based on the Fowler-Nordheim theory.View full abstractDownload PDF (609K) -
Yuichi ISHIKAWA, Shinobu OHKIDO, Toshihiko YOSHIMURA1994 Volume 37 Issue 9 Pages 776-780
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSType 316 stainless steel was oxidized at 475°C and 600°C for 5-15 min in oxygen at a pressure of 10-210-4 Pa. Atom-by-atom compositional determination of the oxide and the oxide-steel interface was accomplished by a recently built position-sensitive atom probe (POSAP).
The analysis shows a gradual development of a triplex oxide structure, the top surface of which is Cr, Ni and Mo rich, the inner region being Fe rich and the interface being Cr, Ni and Mo rich, by increasing the temperature and the time of oxidation. This is accompanied with the development of subnanometer roughness at the oxidesteel interface.
Further work is needed to establish the correlation between this structure and the hydrogen permeation characteristics as well as the composition of the top surface and the hydrogen molecule recombination inhibition, in order to understand the outgassing process in extremely high vacuum and to effectively prepare an extremely low outgassing surface.View full abstractDownload PDF (1346K) -
Shu WATANABE, Masakazu AONO, Shigeki KATO, Hitoshi AKIMICHI, Tomonari ...1994 Volume 37 Issue 9 Pages 781-796
Published: September 20, 1994
Released on J-STAGE: September 29, 2009
JOURNAL FREE ACCESSDownload PDF (1764K)
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