Moderne Lecksucher mit Vakuumtechnik

The International Thermonuclear Experimental Reactor (ITER) vacuum vessel (VV) is one of the critical components of the ITER tokamak fusion reactor. The first sector of the ITER VV was delivered to ITER Organization in 2020, and it is ready to assemble into the tokamak system. After manufacturing the ITER VV, an evaluation should ensure that the components are designed and manufactured to meet the functional requirements, such as vacuum leak tightness and structural integrity. The factory acceptance test (FAT) is essential for confirming acceptance in engineering and manufacturing. This paper introduces the engineering process and technical method of the FAT, which is applied explicitly to the first-of-a-kind ITER VV. We establish a visual inspection, pre-pumping assessment, pressure test, helium (vacuum) leak test, and final dimensional inspection for the FAT. The visual inspection revealed no blockages in the cooling channels of the double walls. The pre-pumping assessment conducted to check the vacuum level and residual gas condition, concluded that the inside of the VV was flawless and thus met the leak test requirements of 1 × 10−8 Pa m3 s−1. We confirmed no leakage or deformation through the pressure test under reduced pressure. The helium leak test demonstrated engineering soundness with leak tightness of 6.08 × 10−9 Pa m3 s−1, which is more stringent than the allowable limit. Furthermore, three-dimensional metrology was utilized to determine the as-built dimensions of the manufactured sector. Due to unavoidable weld deformation and tight tolerances, the as-built result does not perfectly meet the assigned tolerance level. Nevertheless, it can be considered as advanced information for assembly with in-vessel components and other sectors. Based on the conformance and suitability of the suggested FAT for the first ITER VV sector, we will determine the acceptability of the upcoming VV sectors, which will be manufactured and delivered by Korea shortly.

Numerous investigations on extreme ultraviolet (EUV) resist outgassing have been performed using the pressure rise and gas chromatography mass spectrometry (GC–MS) method. However, the reliability of the results obtained with these methods has not been clearly discussed. In this paper, to analyze and verify the reliability of the resist outgassing results, de-protection reaction and photo acid generator's (PAG's) decomposing reaction in the resist film, which are viewed as the main source of resist outgassing, are investigated using the Fourier transform infrared spectroscopy (FT-IR). Analysis was performed on a resist film after EUV exposure, before post exposure bake (PEB). Based on the measured amount of de-protection reaction in the resist film, the amounts of resist outgassing released were calculated. It was found that the resist outgassing amount obtained through FT-IR was somewhere between those obtained using the pressure rise and GC–MS methods results. These similarities in the results substantiate the reliability of resist outgassing amounts obtained through these analysis methods.

Gasket performance for vacuum applications has not been well studied. Although a wealth of sealability data has been generated for pressurized systems, little is done with vacuum conditions. A new test method has been developed to study the sealing performance of gaskets for vacuum services. The tests were conducted on a standard ROTT test rig, where a vacuum chamber surrounding the gasket was created by an air pump and monitored by a pressure gauge capable of measuring pressures down to 0.1 Torr. Two levels of vacuum were used: 50 Torr and 3 Torr. Each tested gasket was compressed to various assembly stresses corresponding to the levels defined in the ROTT procedure. After the gasket was compressed to a desired stress and a target vacuum level was reached, the pumping stopped, and the leak rate was measured, using the pressure rise method. The similar leakage results with two very different vacuum levels confirm that sealing a vacuum system is simply to seal ∼1 bar of air. The air leakage was further compared with the helium leak rates obtained from the standard ROTT test with a pressure of 21 bar to determine the correlation between the two data sets. To better understand the effects of pressure and molecular size of a gas, two additional tests at 2 bar, with helium and with nitrogen, were performed. The comparison among all test data suggests that the gases at relatively low pressures follow a molecular flow behavior up to about 55 MPa of gasket stress on the tested material. As a result, a tightness curve that can be used to estimate the vacuum leakage has been established. For applications involving elevated temperatures, thermal behaviors of gaskets determined by other PVRC tests, such as the HOBT and ARLA, can be used to understand the impact of temperature on vacuum performance. A stress-tightness-temperature framework is proposed that can be used to estimate the tightness and leakage of the gasket at high temperatures. Knowing the air leak rates under different operating conditions, a gasket user will be able to determine the suitability of the gasket for a specific vacuum requirement as well as the optimal assembly stress to maintain the desired vacuum level.

A new noncontaminating dry gas, quantitative test method has been developed that permits gross leak measurements on hermetic packages. It provides rapid testing with a helium leak detector over the leak size range of less than 1 x 10-5to more than I atm-cm3/s with a test gas of ~1 percent helium. The present limitation on dry gas procedures results from the rapid depletion of the test gas from the package interior which prevents detection of the larger leaks. The rapid cycle method attacks this limitation by employing either a rapid transfer of the test package or a rapid gas cycling technique for extending the upper range of the helium leak detector procedure. Theoretical relationships have been derived based on viscous flow to correlate the leak detector reading to leak size. Experimental apparatus is described, and test results are given for a test time of about g s, a measurement precision of 15-35 percent, and a correlation coefficient between theory and test of better than 0.99. The rapid transfer mode of operation can be implemented readily with any helium leak detector equipped for fast pump-down and high helium flow rate.

A Nondestructive Leak Detection Method for Flexible Food Packages Using Hydrogen as a Tracer Gas

The effect of diluent on flame structure and laminar burning speeds of JP-8/oxidizer/diluent premixed flames

Food packages undergo incubation and inspection to ensure that packages are sealed tight and protect the foodfrom contamination and spoilage. Over the years many inspection techniques are used with varying degrees of success. Withthis study, two techniques, ultrasound and pressure differential technique, were assessed and the effectiveness of thesetechniques was quantified. Noncontact, immersion type ultrasonic testing in pulse/echo mode using high frequency soundwaves was evaluated for use in defect detection in the seal area of semirigid cups and polymeric trays. At disparities withinthe seal, sound waves generated by 20MHz ultrasonic transducer were reflected back to the receiver. Received ultrasonicsignals, or echoes, were used to develop Ascan and Cscan presentations. Discontinuities in the seal, short seal, nonbondedareas, imbedded foreign matter such as wire and Teflon in the seal, contaminated seal, and abrasion were detected usingultrasound based on reduced signal strengths.Integrity of mealsreadytoeat (MRE) pouches was inspected using a new pressure (vacuum) differential technique. Thistechnique is based on a threestep approach. To evaluate the system, air was linked into a test chamber through a calibratedneedle valve simulating a leak at different leak rates. A simulated leak that generated values higher than reference, anddependant upon the leak rate, was accepted or rejected by the leak tester. The technique proved to be effective, although,shortsealed nonvacuum packed pound cake pouches failed during subsequent leak testing.

Analysis of low isolation problem in HMC using Ishikawa model: A case study

Gas leaks can cause major accidents resulting in both human injuries and financial losses. Vacuum pressureinduced air leaks lead to the emission of acoustic signals. Vacuum leak tests are implemented in this paper, and signals excited by leaks through apertures of three different diameters are investigated. According to the acoustic emission signal processing theory, several characteristic parameters were utilized to analyze the generation of continuous vacuum leakage acoustic emission signals. Applicable signal characteristics are used to distinguish the vacuumleaks through apertures of different sizes. It can be inferred that the acoustic emission method can detect vacuum gas leaks as they happen, and signal parameter characteristics analysis can be used to distinguish between the different aperture sizes. This paper is of practical significance to the work of acoustic emission vacuum leak detection.

Indoor air pollution is a major issue affecting public health. Due to hot climate, humidity and lack of natural green spaces, life is mostly confined indoors in many countries of the MENA region. Vulnerable population, including young children and senior citizens who spend most of their time indoors, are at risk because of the effects of indoor air quality (IAQ) on their health. An indoor air quality monitoring system is a need of the hour to detect and improve Indoor Air Quality (IAQ). The monitoring systems presently available are bulky, expensive and need periodic calibration to maintain high degree of accuracy. Frequent recalibration of a number of densely deployed individual sensors in the network is a time-consuming and laborious task therefore self-calibration is indispensable. Gas sensors, even if factory-calibrated, tend to drift with time/usage. Therefore these should be regularly calibrated under controlled environments. Calibration may be carried out using test gas mixtures with known composition. Pre-mixed gas cylinders with known composition may be used for the purpose; however this solution is not flexible as the number of calibration points and testing conditions (e.g. effect of temperature and humidity on CO2 sensor) are limited. In the current project, a computer-controlled test and calibration test bed system is being designed and assembled along with temperature controller.Calibration set-up would help in self calibration of the air quality sensors. Calibration curves obtained from proposed calibration test bed are updated automatically and fed into the sensor node through wireless communication without going in the field or replacing the sensor. A computer-controlled test and calibration test bed system is designed and assembled containing the sensor(s) under test and in which gas composition; temperature can be precisely and dynamically controlled. ATMEGA328 micro controller is used to receive the temperature set point from the computer running the test rig.Gas composition, temperature and humidity can be precisely and dynamically controlled in our designed test chamber containing the sensor(s) under test. Given the number of air pollutants that may be present in the atmosphere, up to 6 different gases can be mixed to calibrate the sensor nodes and investigate the issue of cross-sensitivity.Array of 6 gas cylinders, and a gas blending system that has been designed provides continuous variation of mixture composition and temperature. Gas blending is performed using mass-flow controllers, which control a number of different gas streams, including that of an inert gas or pure air. The composition of the test gas mixture resulting from blending is controlled by varying the flow of individual gas components through the mass-flow controllers. The test chamber is fitted with heating elements and temperature sensors to control the gas mixture temperature.The gas composition is controlled by adjusting the flow of gases in each mass flow meter; the set points for these are controlled by a computer running under MATLAB/LABVIEW environment. Each gas line is equipped with the necessary safety valves (shut down valve and one way valve). Additionally, each line has a pressure gauge to monitor the inlet gas pressure.The temperature controller was based on an Arduino Uno microcontroller, tow (2) driver modules that incorporate a H bridge (mosfet), four (4) heaters (each 100 W/24 V), an LM35 temperature sensor, and two (2) fans to ensure uniform temperature inside the test chamber.The micro controller (ATMEGA328) receives the temperature set point from the computer running the test rig; then on/off control with hysteresis is used to control temperature from room temperature to 65 °C with a precision better than 1 °C; Hence temperature is precisely and dynamically controlled so that the sensors be tested under different temperatures.Stainless steel tubes have been used for connecting the various parts. The sealed sensor test chamber included a door that incorporated a rubber seal; all connections to the chamber included rubber seal to ensure that the inner gas composition is controlled only by the mass flow controllers.The inner walls of the chamber are covered with heat insulation material to minimize heat transfer from the chamber and thus minimize heating power requirements. The size of the chamber was selected to allow testing of a complete wireless sensor node that includes all air quality sensors.Sensor measurement readings are compared with a professional air quality measurement analyser named “Gray wolf IAQ Monitor” (Acquired from USA) to verify the effectiveness of the proposed system.In future, humidification of the gas mixture will be considered using different methods, including the saturation method based on water bubble technique. The system will have a fume hood (available in our labs) for safe extraction of gases out of the calibration lab. The test bed will allow:Calibration of procured sensors and sensor nodes.Checking sensors cross-sensitivity and effects of environmental conditions.Training of ANN used with the array of sensors in each node to minimize cross-sensitivity.

Leak detection practice with particular reference to the hydrogen palladium method

A 440 MHz wireless and passive Love-wave-based chemical sensor was developed for CO2 detection. The developed device was composed of a reflective delay line patterned on 41° YX LiNbO3 piezoelectric substrate, a poly(methyl methacrylate) (PMMA) waveguide layer, and Teflon AF 2400 sensitive film. A theoretical model is presented to describe wave propagation in Love wave devices with large piezoelectricity and to allow the design of an optimized structure. In wireless device testing using a network analyzer, infusion of CO2 into the testing chamber induced large phase shifts of the reflection peaks owing to the interaction between the sensing film and the test gas (CO2). Good linearity and repeatability were observed at CO2 concentrations of 0–350 ppm. The obtained sensitivity from the Love wave device was approximately 7.07° ppm-1. The gas response properties of the fabricated Love-wave sensor in terms of linearity and sensitivity were provided, and a comparison to surface acoustic wave devices was also discussed.

Information technology (IT) is a major innovation in the operations of the Philippine national government. It plays an increasingly pivotal role in shaping and influencing the delivery of government services. Hence, effective IT adoption and diffusion in public sector organisations has become an important concern. An understanding of the factors affecting IT adoption could lead to the development of better strategies for introducing IT and maximising its use. This study surveyed national government agencies in the Philippines to determine the factors that facilitate IT adoption and implementation. Built on innovation diffusion and IT implementation studies, a model of organisational-level adoption was developed and tested. The model identified seven variables that could potentially influence IT adoption in the government. Six of these research variables were operationalised using appropriate quantitative measures and multi-item indicators adapted from instruments that have been validated in previous empirical studies. The operational measure for the last variable - information intensity - was specifically developed for this study. The multi-item measures were evaluated and refined using item analysis and factor analysis. Multiple regression analyses were then conducted, to test the research propositions. The results suggest that agencies most receptive to information technology are larger, more open, more information-intensive, and are headed by executives with positive attitudes towards IT.

Macrophage behavior is of great interest in response to tissue injury and promotion of regeneration. With increasing numbers of zebrafish reporter-based assays, new capabilities now exist to characterize macrophage migration, and their responses to biochemical cues, such as reactive oxygen species. Real time detection of macrophage behavior in response to oxidative stress using quantitative measures is currently beyond the scope of commercially available software solutions, presenting a gap in understanding macrophage behavior. To address this gap, we developed an image analysis pipeline solution to provide real time quantitative measures of cellular kinetics and reactive oxygen species content in vivo after tissue injury. This approach, termed Zirmi, differs from current software solutions that may only provide qualitative, single image analysis, or cell tracking solutions. Zirmi is equipped with user-defined algorithm parameters to customize quantitative data measures with visualization checks for an analysis pipeline of time-based changes. Moreover, this pipeline leverages open-source PhagoSight, as an automated keyhole cell tracking solution, to avoid parallel developments and build upon readily available tools. This approach demonstrated standardized space- and time-based quantitative measures of (1) fluorescent probe based oxidative stress and (2) macrophage recruitment kinetic based changes after tissue injury. Zirmi image analysis pipeline performed at execution speeds up to 10-times faster than manual image-based approaches. Automated segmentation methods were comparable to manual methods with a DICE Similarity coefficient > 0.70. Zirmi provides an open-source, quantitative, and non-generic image analysis pipeline. This strategy complements current wide-spread zebrafish strategies, for automated standardizations of analysis and data measures.

When designing a particle accelerator or storage ring the ultimate vacuum pressure is a prime consideration. This is because the better the vacuum, the fewer the number of collisions between the beam and the residual gas molecules, resulting in a longer beam lifetime—a significant criterion. The total pressure readings from BA gauges are useful for pressure distribution data, but an RGA is required to monitor the gas species. The data which RGA’s provide is useful, not only to the vacuum scientist, but everyone connected with the construction and use of a synchrotron.It is usual to employ RGA diagnostics in the early stages of machine construction. A typical sequence of tests would be for leak checking, glow‐discharge and bakeout monitoring, re‐checking for leaks and for contamination (either hydrocarbons or cleaning solvent). When a machine is being commissioned, the RGA can monitor for water to vacuum leaks (water cooled absorbers). Later, when the machine is operational, the RGA can show, via the local...