Negative edge plasma currents in the SINP tokamak

A tokamak plasma discharge having an increase in duration accompanied with enhanced runaway electron flux has been experimentally studied in this paper. The discharges have been obtained by controlling the applied vertical magnetic field (B_v^applB_{\rm{v}}^{\rm{appl}}) to below a critical value. Such discharges have been observed to have ‘negative edge plasma currents’, detected using an internal Rogowskii coil (IRC). We have tried to correlate the runaway behaviour with the negative edge plasma currents and have explained that these observations are a result of beam plasma instabilities.     

High Accuracy Difference Schemes for the Cylindrical Heat Conduction Equation

High accuracy implicit difference methods are derived for thecylindrical heat conduction equation. Some unconditionally stableimplicit formulas are derived. The utility of the new schemesare shown by testing the schemes on two examples.     

Higher Order Difference Formulae for the Numerical Solution of the Heat Conduction Equation

In this note some new higher order stable difference formulaefor the numerical solution of the heat conduction equation aregiven. Stable methods up to order six are derived.     

High Order Numerical Differentiation Type Formulas with an Off-step Point for Stiff Ordinary Differential Equations

Linear k-step implicit numerical differentiation (N.D.) formulaswhich are of order k are stable for k 6 (Henrici, 1962). Inthis paper N.D. type formulas are derived by introducing thevalue of the derivative at an off-step point. It is found thatthe resulting k-step implicit formulas have order k+2 and arestable for k 16. Stiff stability is achieved for k 7, by introducinga suitable corrector at the off-step point. The necessary predictorsare also derived.