The radial density profiles of Ne 10+ and Ne 8+ have been measured with charge exchange recombination spectroscopy in an H-mode discharge in ASDEX Upgrade. When trying to fit the data with an impurity transport code that only takes electronic ionisation and recombination into account, the density of Ne 8+ is too low by more than an order of magnitude indicating that an additional recombination mechanism must be at work. We ascribe the missing recombination channel to charge exchange (CX) reactions between neutral deuterium and the impurity ions, which has long been known to be a very efficient recombination reaction. Including the CXreactions yields a good fit of the ionisation balance and delivers the neutral density profile in the pedestal, which is not known from other diagnostics. Here, the CXreactions lead to a change of the ionisation balance on the whole flux surface and the measurement delivers a flux surface averaged neutral density with the exception of the region very close to the X-point. Furthermore, it leads to an increase of the pedestal radiation of neon since the partially ionised stages can emit line radiation. This amounts to an increase of the radiated power of neon inside of the separatrix by a factor of 5. A similar analysis was done for argon in an H-mode discharge dominated by Ar radiation. Only the CX-recombination in the pedestal can explain the radiated power inside the separatrix, which would be too low by a factor of 2.2 without CX. In addition, the radiances of VUV lines from many charge stages are much better fitted when including the CX-recombination. A simple projection of the impact of CX-recombination to the much hotter ITER pedestals shows that for elements up to Kr, a beneficial increase of edge radiated power per core radiated power and of radiated power per central dilution is obtained, while for Xe and especially for W the effect is weak.

High-β ECH plasma is generated and stably sustained in a magnetospheric configuration, the Ring Trap 1 (RT-1) device, generated by a levitated dipole field magnet. Geomagnetic-field compensation and optimized operation have realized drastic improvements in plasma properties. The maximum local β value has reached 70% and the pressure profiles have a rather steep gradient near the superconducting magnet. Electrons of the high-β plasma typically consist of 70% hot (∼50 keV) and the rest of cold populations. Confinement time of the hot component plasma is 0.5 s with the optimized neutral gas pressure. By removing the coil support structure, the peaked density profile is observed in the strong field region.

Formation of high-b electron cyclotron resonance heating plasma and stable confinement of pure electron plasma have been realized in the Ring Trap 1 device, a magnetospheric configuration generated by a levitated dipole field magnet. The effects of coil levitation resulted in drastic improvements of the confinement properties, and the maximum local b value has exceeded 70%. Hot electrons are major component of electron populations, and its particle confinement time is 0.5 s. Plasma has a peaked density profile in strong field region [H. Saitoh et al., 23rd IAEA Fusion Energy Conference EXC/9-4Rb (2010)]. In pure electron plasma experiment, inward particle diffusion is realized, and electrons are stably trapped for more than 300 s. When the plasma is in turbulent state during beam injection, plasma flow has a shear, which activates the diocotron (Kelvin-Helmholtz) instability. The canonical angular momentum of the particle is not conserved in this phase, realizing the radial diffusion of charged particles across closed magnetic surfaces.

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