Optimised 'hybrid' Scenario H-mode Plasmas for W Radiation Control in Jet with the Be/w Wall

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Within the range of plasma shapes and plasma currents investigated, the electron confinement time, tau_Ee, increases with safety factor, density and negative triangularity similar to the Ohmic heating case. There is little dependence of tau_Ee on the heating location provided power deposition occurs inside the q=1 surface; as power deposition moves out of the inversion surface, tau_Ee decreases. The power-induced energy confinement degradation exponent (tau_Ee~PaP) is as usual: alpha_P ~-0.5. As a general t

The linear relativistic theory of electron cyclotron wave propagation predicts partial absorption of the extraordinary mode at the third electron cyclotron harmonic for typical parameters of present day tokamak plasmas. Since the waves are not totally damped, a quantitative confirmation of such predictions is important to establish this particular resonance scheme firmly for plasma heating and current drive. Specific experiments have been performed on Tore Supra, to measure the optical thickness of the thir

The frequency dependence (13.56-70 MHz) of the ion energy distribution at the ground electrode was measured by mass spectrometry in a symmetrical capacitive impedance at very high frequency allows high levels of plasma power and substrate ion flux while maintaining low levels of ion energy and electrode voltage. The lower limit of ion bombardment energy is fixed by the sheath floating potential at high frequency, in contrast to low frequencies where only the radio frequency voltage amplitude is a determinan

The ideal magnetohydrodynamic stability with respect to localized ballooning modes and the Mercier criterion of a quasihelically symmetric stellarator configuration is investigated. Configurations with an enhanced magnetic mirror and a deeper magnetic well that can be achieved by energizing a set of auxiliary coils have also been analyzed. In all cases, the Mercier criterion imposes a slightly stricter beta limit than the ballooning modes. Using relatively broad pressure profiles, the Mercier criterion yiel

A new finite element (FE) scheme, based on the decomposition of a second order differential equation into a set of first order symplectic (Hamiltonian) equations, is presented and tested on a one-dimensional, driven Sturm-Liouville problem. Error analysis shows improved cubic convergence in the energy norm for piecewise linear ''tent'' elements, as compared to quadratic convergence for the standard and symplectic hybrid (i.e. 'tent' and piecewise constant) FE methods. The convergence deteriorates in the pre

Stable negative ions containing up to sixteen silicon atoms have been measured by mass spectrometry in RF power-modulated silane plasmas for amorphous silicon deposition. These hydrogenated silicon cluster ions reach much higher masses than the positive ions, which have no more than six silicon atoms. This supports the view that negative ions are the precursors to particulate formation in silane plasmas. The time-dependent fluxes of positive and negative ions from the plasma are shown with a 5 mus time reso

Optimised 'hybrid' Scenario H-mode Plasmas for W Radiation Control in Jet with the Be/w Wall

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EFFECT OF LOCALISED ELECTRON CYCLOTRON HEATING ON ENERGY CONFINEMENT AND MHD IN TCV

Measurement of the optical depth at the third electron cyclotron harmonic in tore supra

Sheath impedance effects in very high frequency plasma experiments

Local ideal magnetohydrodynamic stability of a quasihelically symmetric stellarator

Symplectic finite element scheme: Application to a driven problem with a regular singularity

Negative Hydrogenated Silicon Ion Clusters as Particle Precursors in RF Silane Plasma Deposition Experiments