The experimental characteristics of divertor detachment in the JET tokamak with the Mark I pumped divertor are presented for Ohmic, L-mode and ELMy H-mode experiments with the main emphasis on discharges with deuterium fuelling only. The range over which divertor detachment is observed for the various regimes as well as the influence of divertor configuration, direction of the toroidal field, divertor target material and active pumping on detachment will be described. The observed detachment characteristics such as the existence of a considerable electron pressure drop along the field lines in the scrape-off layer, and the compatibility of the decrease in plasma flux to the divertor plate with the observed increase of neutral pressure and the D α emission from the divertor region will be examined in the light of existing results from analytical and numerical models for plasma detachment. Finally, a method to evaluate the degree and window of detachment is proposed and all the observations of the JET Mark I divertor experiments summarised in the light of this new quantitative definition of divertor detachment.

Results are presented from a series of dedicated experiments carried out on JET in tritium, DT, deuterium and hydrogen plasmas to determine the dependence of the H mode power threshold on the plasma isotopic mass. The Pthr ∝ Aeff-1 scaling is established over the whole isotopic range. This result makes it possible for a fusion reactor with a 50:50 DT mixture to access the H mode regime with about 20% less power than that needed in a DD mixture. Results on the first systematic measurements of the power necessary for the transition of the plasma to the type I ELM regime, which occurs after the transition to H mode, are also in agreement with the Aeff-1 scaling. For a subset of discharges, measurements of Te and Ti at the top of the profile pedestal have been obtained, indicating a weak influence of the isotopic mass on the critical edge temperature thought to be necessary for the H mode transition.

A number of experiments with heating of deuterium-tritium (D-T) plasmas using waves in the ion cyclotron range of frequencies (ICRF) have been carried out at the Joint European Torus (JET). The results of these experiments have been analysed by comparing experimentally measured quantities with results of numerical simulations. In particular, four scenarios have been examined: (1) heating of minority (~5−20%) deuterons at the fundamental ion cyclotron frequency, ω ω = cD ; (2) second harmonic heating of tritium, ω ω = 2 cT ; (3) fundamental minority heating of 3 He with a few percent of 3He, and (4) second harmonic heating of deuterium, ω ω = 2 cD . An important aim of the analysis is to assess if the present understanding of the ICRF physics is adequate for predicting the performance of ICRF in D-T plasmas. In general good agreement between experimental results and simulations is found which increases the confidence in predictions of the impact of ICRF heating in future reactors. However, when a relatively high deuterium concentration was used in the ω ω = cD scenario, discrepancies are observed. In order to increase confidence in the simulations, we have studied the sensitivity of the simulation results to various plasma parameters.

A new strictly anaerobic bacterium (strain BAL-lT) has been isolated from a reed bed at Ballarat Goldfields in Australia. A number of different bacteria are able to protect themselves from arsenic. They do so by first reducing arsenate [As(V)] that has entered the cell to arsenite [As(III)] and then transporting the arsenite out of the cell; arsenate reduction does not appear to support growth (7,20). Reduction of arsenate to arsenite in anoxic environments has also been demonstrated (3, 15), but until recently the organisms responsible for this reduction and the mechanisms used were not known.

A modified method for the production of cubic and spherical superparamagnetic nanoparticles is presented. Cubic nanoparticles can be made that are highly monodisperse down to a diameter of 8 nm. A detailed study is presented of the physical properties of these nanoparticles using high-resolution transmission electron microscopy analysis, X-ray powder diffraction, superconducting quantum interference device measurements, and relaxivity measurements performed in a magnetic resonance imaging scanner. It is found that cubic iron oxide nanoparticles have a higher degree of crystallinity and relaxivity (four times higher) than their spherical counterparts. These novel cubic iron oxide nanoparticles show great promise for use in biomedical imaging applications.