No abstract available

[en] On a number of occasions when Joint European Torus (JET) has been vented, the air in the vessel has been sampled prior to opening any flanges. Large amounts (∼ 1.3 x 10²³ atoms) of deuterium are found to have been released from the walls, together with a proportion of the tritium previously produced for (d-d) reaction. A far larger amount of tritium (comparable to the deuterium level above) would be released in the active phase of JET. The amount released can be greatly reduced by carbonising before venting, or by venting the vessel and re-evacuating prior to the venting for personnel access. (author)

[en] Discrepancies in the surface analyses of oxidised or heavily contaminated materials have been observed between X-ray Photoelectron Spectroscopy (XPS) and techniques using electron beams (primarily Auger Electron Spectroscopy (AES)). These discrepancies can be ascribed to the influence of the primary electron beam and to illustrate the various types of electron effects different materials were analysed using XPS and Secondary Ion Mass Spectroscopy (SIMS) before and after large area electron bombardment. The materials used included chrome and stainless steels, nickel, platinum, glass and brass. (author)

[en] Tritium removal is a major unsolved development task for next-step devices with carbon plasma-facing components. The 2-3 order of magnitude increase in duty cycle and associated tritium accumulation rate in a next-step tokamak will place unprecedented demands on tritium removal technology. The associated technical risk can be mitigated only if suitable removal techniques are demonstrated on tokamaks before the construction of a next-step device. This article reviews the history of codeposition, the tritium experience of TFTR (Tokamak Fusion Test Reactor) and JET (Joint European Torus) and the tritium removal rate required to support ITER's planned operational schedule. The merits and shortcomings of various tritium removal techniques are discussed with particular emphasis on oxidation and laser surface heating

[en] Metallic substrates are protected against corrosion, carburisation and carbonaceous deposition by plasma activated vapour deposition of ceramic material coatings thereon. Stainless steel fuel cans used in an Advanced Gas Cooled Reactor are protected e.g. by providing SiO₂ coatings from reaction of silane and CO₂. Carbon steels may also be protected in this way. (author)

[en] The patent relates to the provision of coatings on substrates by sputter ion plating. Tungsten and carbon are co-sputtered from a cathode comprising tungsten and carbon onto a steel substrate. The coating is believed to comprise a mixture of W₂C, to provide hardness, and W, to provide ductility. (U.K.)

[en] Fast and efficient tritium removal is needed for future D-T machines with carbon plasma-facing components. A novel method for tritium release has been demonstrated on co-deposited layers on tiles retrieved from the Tokamak Fusion Test Reactor (TFTR) and from the Joint European Torus (JET). A scanning continuous wave neodymium laser beam was focused to =100 W/mm2 and scanned at high speed over the co-deposits, heating them to temperatures =2000 C for about 10 ms in either air or argon atmospheres. Fiber optic coupling between the laser and scanner was implemented. Up to 87% of the co-deposited tritium was thermally desorbed from the JET and TFTR samples. This technique appears to be a promising in-situ method for tritium removal in a next-step D-T device as it avoids oxidation, the associated de-conditioning of the plasma-facing surfaces, and the expense of processing large quantities of tritium oxide

[en] 'Sputter ion plating' is a new method for ion plating coatings of high integrity. It is especially suited to the deposition of refractory metals, alloys, and compounds and can be applied as well to the more usual low melting materials. The method, as at present developed, employs a simple DC glow discharge in argon to transfer material from appropriate cathodes (targets) by the action of ion bombardment (sputtering) to substrates suitably mounted within the soft vacuum chamber. Success depends on correct design of the chamber and a continuous throughput of purified gas at a pressure of ca 10^-4 bar. The chamber itself, or a liner within it, is arranged to operate at elevated temperature, e.g. 200⁰C or more, and the connection to the pump is designed to prevent back diffusion of contaminating gases and vapours. Thus, although only a simple mechanical pump is needed to maintain the soft vacuum required for the process, pure gas conditions are readily achieved in the coating region. Cathodes may be distributed in sheet form, or other geometry as required, to give high throwing power and a high degree of coating uniformity; rotation or movement of substrates is not normally needed. In addition to direct sputtering of compound cathodes (or cathodes comprising more than one element), chemically active gases may be admitted in controlled concentration to deposit compounds by reactive sputtering. Coating rates at present lie in the range 0.5 to 5 μm/hr. A negative bias is applied to the substrates for ion cleaning and subsequent control of coating structure during deposition. Adherence of the coating to the substrate is usually high if ion cleaning is properly conducted

[en] Components of the JET Mk-II Gas Box divertor have been analysed ex-situ after 18 months of operation with that divertor structure. The aim was to give an account on the distribution of the retained fuel along the poloidal cross-section of the divertor and, in particular, in the septum. Inside the gas box thick hydrogenated deposits were formed only on surfaces located in the near-plasma region from the inner divertor side whereas very little deposition was detected deep inside the gas box, i.e. on the support and divider plates

[en] Material migration has received renewed interest due to tritium retention associated with carbon transport to remote vessel locations. Those results influence the desirability of carbon usage on ITER. Subsequently, additional experiments have been performed, including tracer experiments attempting to identify material migration from specific locations. In this paper, EDGE2D models a well-diagnosed JET¹³C tracer migration experiment. The role of SOL flows upon the migration patterns is identified