Demonstrating improved confinement of energetic ions is one of the key goals of the Wendelstein 7-X (W7-X) stellarator. In the past campaigns, measuring confined fast ions has proven to be challenging. Future deuterium campaigns would open up the option of using fusion-produced neutrons to indirectly observe confined fast ions. There are two neutron populations: 2.45 MeV neutrons from thermonuclear and beam-target fusion, and 14.1 MeV neutrons from DT reactions between tritium fusion products and bulk deuterium. The 14.1 MeV neutron signal can be measured using a scintillating fiber neutron detector, whereas the overall neutron rate is monitored by common radiation safety detectors, for instance fission chambers. The fusion rates are dependent on the slowing-down distribution of the deuterium and tritium ions, which in turn depend on the magnetic configuration via fast ion orbits. In this work, we investigate the effect of magnetic configuration on neutron production rates in W7-X. The neutral beam injection, beam and triton slowing-down distributions, and the fusion reactivity are simulated with the ASCOT suite of codes. The results indicate that the magnetic configuration has only a small effect on the production of 2.45 MeV neutrons from DD fusion and, particularly, on the 14.1 MeV neutron production rates. Despite triton losses of up to 50 %, the amount of 14.1 MeV neutrons produced might be sufficient for a time-resolved detection using a scintillating fiber detector, although only in high-performance discharges.

High-efficiency refuelling of ELMy H-mode tokamak discharges with solid deuterium pellets injected from the magnetic high-field side is demonstrated. Compared to standard low-field side injection, the fuelling efficiency was enhanced by a factor of 4, the pellet penetration more than 2 times. This experimental result can be qualitatively explained by the magnetic force pushing a diamagnetic plasma cloud towards lower magnetic field, causing rapid particle loss for shallow lowfield side injection, but enhancing fuelling efficiency and pellet penetration for high-field side injection.[S0031-9007 (97)03857-X] PACS numbers: 28.52.Cx, 52.55.FaNext generation fusion devices like ITER will have to operate at densities well beyond the Greenwald limit obtained in present day tokamaks with gas refuelling [1]. Though the detailed nature of this empirical limit is still under discussion, it was shown that it can easily be overcome by injection of frozen hydrogen isotope pellets penetrating much deeper than cold gas particles (e.g., Franck-Condon atoms from molecule disintegration) [2]. In discharges with high heating power and especially in type-I ELMy H-mode plasmas with high edge temperatures, a large fraction of the deposited material was rapidly expelled from the plasma column [3], resulting in significantly reduced fuelling efficiencies´f especially with shallow penetration [2,4]. In Ref. [4] it was shown that at least part of this mass was lost in the vicinity of the injection point along a trace aligned with the helical magnetic field (please note the correct sequence of Figs. 3(a) and 3(b) is reproduced in the corrigendum).In this and all previous experiments, pellets were injected from the magnetic low-field side (LFS), i.e., from the torus outside, which is easily accessible in a tokamak. It was therefore argued [4] that, because of the unfavorable toroidal curvature, part of the diamagnetic pellet plasma cloud could have been expelled before it was captured by the background plasma. If so, injection from the magnetic high-field side (HFS), i.e., the torus inside, should be much superior, since the same effect would help to transport the pellet mass deeper into the bulk plasma. In order to clarify this question, experiments have been conducted in ASDEX Upgrade where pellets were injected from both sides into H-mode plasmas and f as well as pellet penetration depths were compared. ASDEX Upgrade is a midsize divertor tokamak (tokamak radius R 0 1.65 m, plasma radius a 0.5 m, V plasma 13 m 3 , plasma elongation b͞a 1.6; singlenull divertor). Wall elements in contact with the plasma are covered by graphite tiles, the divertor target plates were tungsten coated. Calibrated valves mounted at the vessel midplane are used for gas puffing, and turbomolecular pumps with a pumping speed of 14 m 3 ͞s for D 2 (deuterium) gas to control particle exhaust.The experiments described here were carried out in D with plasma currents I p 0.8 1.2 MA, toroidal magnetic field jB t j 1.7 2.5 T, safety factor q 95 2.7 4.2, and additional bea...

In the last decade, several programs for the treatment of cannabis-related disorders were developed. Until now, no information is available on the efficacy of Internet-based counseling approaches for this target group. This article describes the evaluation of "quit the shit," a web-based intervention developed to help young people to quit or reduce their cannabis use significantly. Cannabis users seeking web-based treatment were included in a two-arm controlled trial conducted on a website for drug-related information and prevention. After the baseline assessment, members of the treatment condition were randomized to a 50-day intervention program. Other trial participants were put on a waiting list. A post-test was conducted 3 months after randomization. Of all 1,292 subjects included in the trial, a total of 206 participants took part at the post-test. Per-protocol- and intention-to-treat analyses were conducted. Members of the treatment condition showed a significantly stronger reduction in cannabis use (primary outcome) than the control group. In the per-protocol analyses, moderate-to-strong effects were found for the reduction of the frequency and the reduction of the quantity of consumed cannabis. Small-to-moderate effects were observed on the secondary outcomes (use-related self-efficacy, anxiety, depression, and life satisfaction). Despite limitations concerning the interpretation of the results, the intervention seems to offer an effective treatment option for persons with cannabis-related problems.

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