[en] The retention of oxygen implanted in graphite at 1.5 and 3 keV was measured as a function of fluence. At fluences less than 10¹⁶ O/cm² the oxygen was all retained, but at higher fluences the retention saturated. Models describing the retention are discussed which include the effects of sputtering and a saturation limit to the local oxygen concentration. Thermal release of oxygen implanted to saturation at room temperature began at 250⁰C and was 90% complete by 750⁰C

[en] Microstructure and low-cycle fatigue (LCF) behavior of A319 cast alloy were investigated in this work. Microstructure analysis indicated that both degassing and hot isostatic pressing (HIPing) process could help to reduce and eliminate porosity. The strain-controlled low-cycle fatigue tests were conducted at total strain amplitude ranging from 0.2% to 0.4%. The stress-strain hysteresis loops were acquired and the effect of HIPing and degassing on cyclic deformation behavior was analyzed combining the cyclic stress response curves. Moreover, the effect of HIPing and degassing on LCF life was analyzed, and a fatigue life model based on the area fraction of defects was proposed which was found to be suitable to predict life. Finally, the fatigue fractography observation showed that the presence of porosity could accelerate the initiation and propagation of cracks and the fatigue failure of materials. (paper)

[en] High performance operating regimes have been achieved on NSTX (National Spherical Torus Experiment) through impurity control and wall-conditioning techniques. These techniques include HeGDC-aided boronization using deuterated trimethylboron, inter-discharge HeGDC, 350 C PFC bake-out followed by D2 and HeGDC, and experiments to test fueling discharges with either a He-trimethylboron mixture or pure trimethylboron. The impact of this impurity and density control program on recent advances in NSTX plasma performance is discussed

[en] Degassing effects of ultrasonic and vacuum processes on high conductivity hard drawn aluminum melt were studied. Results showed that the degassing efficiency improved with the increase of ultrasonic power within certain range, stabilizing at 70% with 240W. For vacuum degassing process, hydrogen content of aluminum melt decreased with the loading time and was linear with logarithm of vacuum degree. Comparison of degassing effects of ultrasonic, vacuum, vacuum-ultrasonic degassing process showed that vacuum-ultrasonic process presented optimal effect. (paper)

[en] A technique for degassing the vacuum chamber of a tokamak-type device which utilizes the heating of high vacuum tract elements with a simultaneous pumping out is described. To improve chamber's operation reliability and to reduce the duration of the period required to attain the established temperature conditions, the heating of bellows elements of the chamber is performed by repeatedly switching on induction heating up for short time intervals. The duration of the heatinq up is controlled by the value of the permissible temperature drop between bellows and ring element of the chamber as well as by pressure value in the chamber. Control of power supplied to branch pipe heaters is executed in the function of the permissible temperature drop between branch pipes and ring elements

[en] The EMIS PARSIFAL can work with two different sources: A thermoionization source or a plasma source. For the former, the work function of tungsten crucibles is enhanced by previous heating at 2850deg C for two hours. Outgassing of both source types after cleaning required days' occupancy of PARSIFAL. A special bench, a copy of the separator source block with its supplies, was designed and built for these purposes in 1990. The Dollar 170 000 investment relieves PARSIFAL from secondary tasks and saves approximately 60 days per year. (orig.)

[en] Experiments show that conditions exist whereby graphite can be baked out sufficiently so that further gas evolution is not of significance. POCO, GIS, and Pyrocarb all have almost the same activation energies for release and all exhibit the property of being easier to clean up after an initial high temperature bake-out. Data presented indicate that the release rate follows a logarithmic rate law

[en] When transporting highly radioactive material, it is vital to provide a successful delivery. Without proper containment, radioactive materials can become exposed to the surrounding environment and pose a serious threat. To ensure a safe transition of radioactive material, packaging components must be able to withstand high levels of heat during the event of a fire while maintaining the integrity of the structure to safety contain the radioactive material. Various types of polyurethane and silicone have been selected to observe at high temperatures to analyze outgassing characteristics of the materials.

[en] The article deals with forming an aerodynamic model of worked out areas serving to calculate leak in it taking into account degassing. (author)

[en] The status of the design and fabrication of a prototype sector of the storage ring vacuum system for the Advanced Photon Source is described. The 26.5-m-long prototype sector will be assembled within a full-scale magnet and tunnel mockup to study interspacial component relationships for maintenance, as well as the vacuum system operational performance. Each completed vacuum section is mounted as an integral part of the modular structure that contains the magnets and magnet power supplies on a common base. Unique automatic machine welding designs and techniques are employed in the fabrication of the aluminium vacuum chambers from extrusions. Special chamber bending procedures and measurements checks are used to maintain the required flatness of the insider chamber light gap surfaces. Photo-electron yields due to low-energy photons in the narrow channel gap of the vacuum chamber and their potential effects on the overall outgassing rate are found to be negligible. 9 refs., 5 figs