Effect of neutral and ion temperatures in the 2D fluid model for the RF heated ion source SPIDER

This paper presents the basic physical and numerical principles of a fluid model implemented into numerical code FSFS2D (Fluid solver for source for the production of ions of deuterium extracted from rf plasma (SPIDER) in 2D) used for simulating the SPIDER negative ion source. It gives self-consistent 2D description of the source, including the neutral gas flow, plasma chemistry, radio-frequency (RF) coupling in the source driver and plasma transport through the magnetic filter. This paper fo...

Plasma properties in negative-ion beam sources for fusion: recent results and challenges in view of ITER

Approximation with rational and rescaled kernels: new steps forward

The aim of this paper is to present new insights into Rational Radial Basis Function (RRBF) approximations and their localized rescaled counterparts. After some necessary notation, we briefly recall the essence of stable computational techniques for overcoming the ill-conditioning of the kernel matrices, as well as the ones that explore stable bases. RRBFs are then introduced, and their benefits are described. We discuss Variably Scaled Kernels, which provide a more flexible tool for approxim...

A note on the direct approximation of derivatives in rational radial basis functions partition of unity method and its application to the convection-diffusion equations

This paper proposes a direct rational radial basis functions partition of unity (D-RRBF-PU) approach to compute derivatives of functions with steep gradients or discontinuities. The novelty of the method concerns how derivatives are approximated. More precisely, all derivatives of the partition of unity weight functions are eliminated while we compute the derivatives of the local rational approximants in each patch. As a result, approximate derivatives are obtained more easily and quickly tha...