Isotope effect and multiscale physics in fusion plasmas.

The mechanism governing the impact of the mass isotope on plasma confinement is still one of the main scientific conundrums facing the magnetic fusion community after more than thirty years of intense research. We have investigated the properties of local turbulence and long-range correlations in hydrogen and deuterium plasmas in the TEXTOR tokamak. Experimental findings have shown a systematic increasing in the amplitude of long-range correlations during the transition from hydrogen to deuterium dominated plasmas. These results provide the first direct experimental evidence of the importance of multiscale physics for unraveling the physics of the isotope effect in fusion plasmas.

Development of the gas-puff imaging diagnostic in the TEXTOR tokamak.

Gas puff imaging (GPI) [S. J. Zweben, D. P. Stotler et al., Phys. Plasmas 9, 1981 (2002); R. J. Maqueda, G. A. Wurden et al., Rev. Sci. Instrum. 74, 2020 (2003)] is a powerful diagnostic that permits a two-dimensional measurement of turbulence in the edge region of a fusion plasma and is based on the observation of the local emission of a neutral gas, actively puffed into the periphery of the plasma. The developed in-vessel GPI telescope observes the emission from the puffed gas along local (at the puff) magnetic field lines. The GPI telescope is specially designed to operate in severe TEXTOR conditions and can be treated as a prototype for the GPI systems on next generation machines. Also, the gas puff nozzle is designed to have a lower divergence of the gas flow than previous GPI diagnostics. The resulting images show poloidally and radially propagating structures, which are associated with plasma blobs. We demonstrate that the local gas puff does not disturb plasma properties. Our results indicate also that the neutral gas emission intensity is more sensitive to the electron density than the electron temperature. Here, we present implementation details of the GPI system on TEXTOR and discuss some design and diagnostic issues related to the development of GPI systems in general.

The use of night orthoses in cerebral palsy treatment: sleep disturbance in children and parental burden or not?

In this study, we investigated whether (1) children with cerebral palsy (CP) using night orthoses experience more sleep disturbance than those not using night orthoses, (2) parental personality is related to the experienced parental burden of night orthoses, and (3) parental sense of competence in the parenting role mediates the relation between parental personality and parental burden. Eighty-two Flemish children with CP (55 using/27 not using night orthoses) with a mean age of 9 years and 10 months (GMFCS level I-V) participated in this cross-sectional questionnaire study, using the Sleep Disturbance Scale (SDSC), Parenting Stress Index (PSI), Big Five Inventory (BFI) and a newly developed inventory to assess the parental burden of night orthoses. Multivariate analysis of covariance revealed no statistical significant differences in sleep disturbance between children using/not using night orthoses. These findings are positive as the use of night orthoses are presumed to be important in providing adequate postural care in children with CP. Extraverted and emotionally stable parents experienced less parental burden. Mediation analysis revealed that parental sense of competence partially mediated the relation between parental personality and the parental burden. These results suggest that integrating parental sense of competence in treatment programs can improve the understanding of experienced burden. Implications of such integrations for therapy are discussed.

Influence of the static Dynamic Ergodic Divertor on edge turbulence properties in TEXTOR.

Systematic measurements on the edge turbulence and turbulent transport have been made by Langmuir probe arrays on TEXTOR under various static Dynamic Ergodic Divertor (DED) configurations. Common features are observed. With the DED, in the ergodic zone the local turbulent flux reverses sign from radially outwards to inwards. The turbulence properties are profoundly modified by energy redistribution in frequency spectra and suppression of large scale eddies. The fluctuation poloidal phase velocity changes direction from electron to ion diamagnetic drift, consistent with the observed reversal of the Er x B flow. In the laminar region, the turbulence is found to react to an observed reduced flow shear.