Vacuum Pipe Research Articles

A low cost, 400 G 18″ (45.7 cm) gap C-magnet using permanent magnet technology

A low-cost, low-field (400 G) 18″ (45.7 cm) gap C-magnet using permanent magnets has been constructed. This magnet was used in a calibration study in the E799/E832 (KTeV) beamline at Fermilab. The C-magnet configuration was selected for ease of installation around an existing vacuum pipe. An advantage of the permanent magnet design is that no water or power connections are needed.

Single-bunch beam property for FEL on the UVSOR storage ring

Single-bunch beam properties such as bunch lengthening and instability that are very important factors to develop storage ring free electron lasers (SRFEL) have been investigated on the UVSOR electron storage ring. Data were analyzed based on a model of potential-well distortion due to the impedance of the vacuum pipe. The inductive impedance was obtained to be 40 nH which is approximately 10 times larger than that of a newly constructed 3rd generation light source. In an operation with negative momentum compaction factor, the bunch shortening was observed which is also explained by which the inductive impedance dominates the single bunch property on the UVSOR ring.

Recent results from the CMD-2 detector at VEPP-2M collider

The general purpose detector CMD-2 is taking data at the e + e − collider VEPP-2M at Novosibirsk in the energy range 360 –1400 MeV. The integrated luminosity ≈ 4000 nb −1 of around φ meson mass (5.0 × 10 6 of φ's) and ≈ 500 nb −1 in the 600–1000 MeV range have been collected. A latest analysis of the rate decays of φ meson and the. K S K L coupled decays based on 30% of available data is presented in this paper. A selection of K L → π + π − decays demonstrated background from semileptionic K L decays and the regeneration of K L into K S at the Be vacuum pipe. The regenration cross section for 110 MeV/c kaons has been measured along with angular distribution.

Performance testing and evaluation of solid absorption solar cooling unit

Based on solid-vapour intermittent absorption system, DORNIER a German Firm designed and fabricated a solar cooling unit, which utilizes thermal energy supplied by heat pipe vacuum tube solar collectors through thermosyphonic flow of water. The unit of 1.5 kWh/day cooling capacity uses ammonia as a refrigerant and IMPEX material as absorbent and does not have any moving part requiring no auxiliary energy. The IMPEX material (80% SrCl 2 and 20% Graphite) has high heat and mass transfer coefficient as well as high absorption capacity. Detailed experiments were performed on a unit in Delhi under real field conditions followed by theoretical analysis. Theoretical maximum overall COP of the unit is 0.143, and it depends upon the climatic conditions. Under field conditions, it was found that if the maximum daytime ambient temperature was 30°C and night time temperature 20°C, it took three sunny days to freeze water in the cooling box. After the second day, the temperature inside the cooling box remained 1°C. The overall COP was found to be 0.081 only. The automatic control valve based on mechanical/thermal principles however has defects and the problem of corrosion of the sealings needs to be solved. In climates where day time temperatures are high (Delhi summer 43°C–47°C during the day, 30°C–35°C during the night) and solar radiation relatively low (4–5 kWh/m 2d) because of pollution and sand in the atmosphere, it is most unlikely that pressure in the ammonia circuit can reach values at which ammonia vapours start to condense. The unit, needs to be redesigned for such conditions.

Sustainable water and waste management in urban areas

Sewerage system and centralised aerobic wastewater treatment plants (WTP) should not be considered as the only possible solution for sanitation. Systems with source control can avoid many problems of the end-of-pipe technology by respecting different qualities of wastewater and by treating them appropriately for reuse. Different qualities of waste and wastewater in human settlements and appropriate treatment technologies can be: 1. low diluted faeces with/without urine and bio waste (composter or anaerobic digester), 2. grey ·water/aerobic biofilm plant, 3. storm water (usage and infiltration) and 4. non-biodegradable waste (reuse as raw material). In order to perform resource management, the material originating from agriculture should be returned to the soil as fertiliser. Of similar importance is the organic material. This helps maintaining or building up humus and creates a sink for carbon when the C-content in the soil is increased. Energy will be saved, too: energy-intensive aerobic treatment with nitrification is obsolete as well as the production of the respective amount of replaced artificial fertiliser. A pilot project for a new settlement for about 300 inhabitants in Lübeck, Germany, shall demonstrate the feasibility of a new integrated system with vacuum toilets and pipes for the collection of black water. This will be mixed with shredded bio waste and fed to a semicentralised biogas plant that produces liquid fertiliser without dewatering. Grey water will be treated in decentralised biofilm systems. Storm water is collected, retained and infiltrated in a trench system. This way the expensive centralised sewerage system can be avoided for this settlement.

Structural materials for ITER in-vessel component design

The materials proposed for ITER in-vessel components have to exhibit adequate performance for the operating lifetime of the reactor or for specified replacement intervals. Estimates show that maximum irradiation dose to be up to 5–7 dpa (for 1 MWa/m 2 in the basic performance phase (BPP)) within a temperature range from 20 to 300°C. Austenitic SS 316LN-ITER Grade was defined as a reference option for the vacuum vessel, blanket, primary wall, pipe lines and divertor body. Conventional technologies and mill products are proposed for blanket, back plate and manifold manufacturing. HIPing is proposed as a reference manufacturing method for the primary wall and blanket and as an option for the divertor body. The existing data show that mechanical properties of HIPed SS are no worse than those of forged 316LN SS. Irradiation will result in property changes. Minimum ductility has been observed after irradiation in an approximate temperature range between 250 and 350°C, for doses of 5–10 dpa. In spite of radiation-induced changes in tensile deformation behavior, the fracture remains ductile. Irradiation assisted corrosion cracking is a concern for high doses of irradiation and at high temperatures. Re-welding is one of the critical issues because of the need to replace failed components. It is also being considered for the replacement of shielding blanket modules by breeding modules after the BPP. Estimates of radiation damage at the locations for re-welding show that the dose will not exceed 0.05 dpa (with He generation of 1 appm) for the manifold and 0.01 dpa (with He generation 0.1 appm) for the back plate for the BPP of ITER operation. Existing experimental data show that these levels will not result in property changes for SS; however, neutron irradiation and He generation promote crack formation in the heat affected zone during welding. Cu based alloys, DS-Cu (Glidcop A125) and PHCu CuCrZr bronze) are proposed as a structural materials for high heat flux components of limiter, baffle, divertor and primary wall. Irradiation significantly changes the mechanical properties, and the electrical and thermal conductivity of these alloys. The ductibility of high strength Cu alloys is reduced at relatively low doses (< 0.2 dpa) for irradiation temperature ∼ < 150°C. For higher doses of irradiation it remains at the low (saturated) level. This effect is exhibited by both DS-Cu and PH-Cu alloys. For higher temperatures of irradiation, an increase of ductility and decrease of strength are observed resulting from radiation-induced microstructural instabilities. The ‘softening’ temperatures for CuCrZr alloys is ca. 300–400°C.

Scattered light noise in gravitational wave interferometric detectors: Coherent effects.

Large interferometric detectors of gravitational waves involve high power light beams stored in optical resonators or Fabry-Perot cavities, installed in km long vacuum pipes. Scattering of light by mirrors, interaction of the scattered light with the walls of the vacuum vessel, and final rescattering on any mirror is a source of noise in such antennas. We present some results obtained within the framework of a coherent approach of scattered light propagation using a coherence function allowing us to study, namely, the effects of small reflecting surfaces along the tube, of diffraction, and of reflection by eventual baffle edges.

Testing general relativity inside a mass distribution using an interferometer

We propose an experiment to test general relativity in which the light beam in one arm of a large interferometer runs by means of a small vacuum pipe through the center of a large sphere of water. The phase shift caused by the reduction of the propagation velocity of the light in the gravitational field of the sphere will be measurable with near-future technology. This phase shift has a surprisingly large sensitivity to the details of the metric inside the sphere where the energy-momentum tensor is non-zero. The interior metric of general relativity yields results about 25 per cent higher than a comparison metric which has the same Newtonian gravitational field. This allows us to investigate general relativity experimentally with non-zero energy-momentum tensor for the first time.

Gravity changes at the Esashi Gravity Station observed by the absolute gravimeter with a rotating vacuum pipe

We have developed an absolute gravimeter with a rotating vacuum pipe. The rotating vacuum pipe has an angular velocity high enough to keep a falling object to the end of it, where the falling object begins to drop by stopping the pipe vertical. We put a Michelson interferometer with a stabilized He-Ne laser under the vacuum pipe to measure the position of the falling object at every 1 ms synchronized with a rubidium frequency standard. This absolute gravimeter has succeeded in the measurements with a drop-to-drop scatter of 1.9 × 10−7ms−2 (19µGal) at the Esashi Gravity Station in the end of 1989 and also has succeeded in the continuous measurements for a week at the same place in December 1991. During the three-year experiments, the measured gravity values have gradually increased until the end of 1991 and then gained in the rate of increase, although we cannot deny the possibility of instrumental origin. The comparisons with other types of absolute gravimeters showed that the values obtained by the absolute gravimeter with a rotating vacuum pipe are close to those obtained by the absolute gravimeters ILOM#1 and NAOM#2 and are lower than those obtained by JILA#4, though the times of comparisons are different.

Prototype development of a warm bore insert for the LHC magnet measurements

To allow the measurements of the superconducting LHC magnets up to their nominal field with well-proven, standard techniques, easy access into the apertures is required at ambient temperature and atmospheric pressure. A warm bore anti-cryostat is inserted into the cold bore vacuum pipe of the magnet, where the evacuated radial gap between these two parts serves as thermal insulation. To allow for maximum accessible cross-section during the measurements, the small radial gap of 3.5 mm has to accommodate superinsulation, support spacers and electrical heaters for the thermalization. Design aspects, related to the high magnetic fields, quenches, mechanical loads, vacuum, reliability and ease of handling have to be addressed. The design of the anti-cryostat and the cryogenic test of a prototype model are described. The heat load on the cold mass of the magnet by this prototype was below one watt per meter. >

Genotoxicity studies in semiconductor industry. 1. In vitro mutagenicity and genotoxicity studies of waste samples resulting from plasma etching.

Solid waste samples taken from the etching reactor, the turbo pump, and the waste air system of a plasma etching technology line in semiconductor production were studied as to their genotoxic properties in a bacterial repair test, in the Ames/Salmonella microsome assay, in the SOS chromotest, in primary mouse hepatocytes, and in Chinese hamster V79 cell cultures. All three waste samples were found to be active by inducing of unscheduled DNA-synthesis in mouse hepatocytes in vitro. In the bacterial rec-type repair test with Proteus mirabilis, waste samples taken from the turbo pump and the vacuum pipe system were not genotoxic. The waste sample taken from the chlorine-mediated plasma reactor was clearly positive in the bacterial repair assay and in the SOS chromotest wit Escherichia coli. Mutagenic activity was demonstrated for all samples in the presence and absence of S9 mix made from mouse liver homogenate. Again, highest mutagenic activity was recorded for the waste sample taken from the plasma reactor, while samples collected from the turbo pump and from the waste air system before dilution and liberation of the air were less mutagenic. For all samples chromosomal damage in V79 cells was not detected, indicating absence of clastogenic activity in vitro. Altogether, these results indicate generation of genotoxic and mutagenic products as a consequence of chlorine-mediated plasma etching in the microelectronics industry and the presence of genotoxins even in places distant from the plasma reactor. Occupational exposure can be expected both from the precipitated wastes and from chemicals reaching the environment with the air stream.

Present status of TARN-II vacuum system

The heavy ion cooler synchrotron, TARN-II, has been operated for studies of accelerator technology and atomic physics since 1989 at the Institute for Nuclear Study, University of Tokyo. The ring has a circumference of 78 m and the vacuum pipe is made of SUS 316L stainless steel. The vacuum system consists of ion pumps, titanium sublimation pumps and turbo-molecular pumps. Beam experiments like acceleration, electron cooling, and extraction have been carried out at a mean pressure of the order of 10 −10 torr. In 1991, the upgrading of TARN-II vacuum system had been performed by adding ion pumps and titanium sublimation pumps in order to promote the experiments using heavy ion beams. Ion beams such as p, D, H 2 +, H 3 +, 3He +, 4He 2+, HD 2 +, 4HeH +, 14N 5+ and 14N 7+ have been injected and circulated in the ring so far.

The straight vacuum chambers of the SRRC 1.3 GeV electron storage ring

The straight vacuum chambers (S-chamber) of the SRRC 1.3 GeV electron storage ring are designed, fabricated and tested. Vacuum pipes, bellows, flanges, pumping ports and most of the other components are made of aluminum. The S-chambers are designed to have the function of reducing radio-frequency ( rf) impedance and removing the heat created by synchrotron radiation. A stringent tungsten-inert gas (TIG) welding process is performed to minimize the deformations in both longitudinal and transverse directions. In order to achieve uhv, in situ bakeout by tape heaters is adopted. The testing results showed that the designs for removing the baking-related problems work well.

Fabrication of a Molded Type High Power Septum Magnet.

A couple of pulse septum magnets is used to inject a 800MeV electron into the superconducting electron storage ring of Mitsubishi Electric Corp. The beam orbit simulation indicates that the apparent septum width of the magnet should be less than 3mm to obtain the good injection efficiency into the ring. To perform the requirement and overcome the problems of heat dissipation and Lorentz force, the molded type septum magnet is designed and fabricated.The fabricated magnet is 1m long and has an aperture of 10mm height and 10mm width. The vacuum pipe of 0.3mm thickness is settled through the aperture for beam transport line (HBT line). The magnet is excited by a single turn coil to 1.8T at 17kA of a sine wave with a width of 4ms which provides a peak field uniformity of 0.1% for a duration of 12μs as required for injection.As for the apparent septum width, the width of 2.5mm, which includes the coil, coil holder, and thickness of the vacuum chamber of storage ring and HBT line, is achieved.The experiment of high energy electron beam transportation through the magnet has been done and the stable extraction from the magnet is observed.

Development and test of a large silicon strip system for a hadron collider Beauty trigger

Large apecture forward spectrometers with planar geometry perpendicular to the beam line are the natural detectors to accomodate the expected forward peaking of Beauty particle production at high energy hadron colliders. We have designed, built and tested a prototype planar silicon strip vertex detector for triggering such a spectrometer system. The test system consisted of 43 000 channels, configured in six planes, each with four quadrants, perpendicular to the beam line and installed inside the SPS-collider vacuum pipe at the center of an interaction region. Events recorded with the rf shield of the silicon system 1.5 mm from the circulating beams show negligible event-unrelated background.

Scattering of thermal photons by a 46 GeV positron beam at LEP

The scattering of thermal photons present in the vacuum pipe of LEP against the high energy positron beam has been detected. The spectrum of the back-scattered photons is presented for a positron beam energy of 46.1 GeV. Measurements have been performed in the interaction region 1 with the LEP-5 experiment calorimeter.

Monte Carlo simulation of synchrotron radiation transport and calculation of dose to the components of a high-energy accelerator

An electron-positron collider (LEP) has recently been put into operation at CERN. Two 46 GeV beams circulate around the 27 km accelerator ring and these produce intense synchrotron radiation with photon energies up to more than 1 MeV. A lead shiedl 8 mm thick has been provided in most places around the vacuum chamber to minimize radiation damage to sensitive machine components. Monte-Carlo techniques using a modified version of MORSE have been used to estimate dose-rate levels in the tunnel due to radiation escaping from the vacuum pipe and scattered by magnets and the tunnel walls. The results have been confirmed by dosimetry measurements.

Monte Carlo simulations of molecular gas flow: some applications in accelerator vacuum technology using a versatile personal computer program

The Monte Carlo technique has been used extensively in the past to solve the problem of molecular flow through vacuum pipes or structures with specific boundary conditions for which analytical or even approximate solutions do not exist. Starting from a specific program written in 1975, the idea germinated over the years to produce handy, rather general, problem solving applications capable of running efficiently on modern microcomputers, mainly for ease of transportability and interactivity. Here, the latest version is described. The capabilities and limitations of these tools are presented through a few practical cases of conductance and pumping speed calculations pertinent to accelerator vacuum technology.

New design of absolute gravimeter for continuous observations

We describe a new absolute gravimeter, which is suitable for long-term continuous observations. It uses laser interferometry to measure the acceleration of a falling corner cube with reference to atomic standards. Between drops, the corner cube is lifted to the top by rotating the vacuum pipe around a horizontal axis with an angular velocity high enough to keep the cube fixed by centrifugal force. This method has an enormous advantage for making a large number of measurements since there is no complicated mechanism inside the vacuum pipe. This absolute gravimeter seems to have no source of systematic error which will exceed one part in 109 if we can reduce the amplitude of the mechanical vibration to less than about 1.5 nm. We describe here the principle and the results of the experiments that we have made to date.

Construction and performance of silicon detectors for the small angle spectrometers of the collider detector of fermilab

The manufacturing process of a series of position sensitive silicon detectors is described together with the tests performed to optimize the performance of the detectors. The detectors are Schottky diodes with strips on the ohmic contract which allow to determine the position of the incoming ionizing particles by charge partition. Four detectors were assembled in a telescope and tested inside the vacuum pipe of the Tevatron Collider at Fermilab. The system is a prototype of the Small Angle Silicon Spectrometer, designed primarily to study p- p elastic and diffractive cross sections, and is a part of the Collider Detector of Fermilab (CDF). Several tests were performed to check the efficiency and the linearity of response of various regions of the detectors. Scans of the beam halo were also done both in high and low β optics to check how close to the beam the detectors could be operated. Finally, the dependence of the detector response on temperature and integrated radiation dose was investigated.