Particle transport simulations based on selfconsistency of pressure profiles in tokamaks

Simulation of particle and heat transport was performed with the ASTRA code. The equations for the electron temperature and density, ion temperature and current diffusion were solved. For the heat transport we used the canonical profiles model. Three T-10 pulses with toroidal magnetic field 2.5 T, plasma current 250…255 kA, initial average density 1.3, 2.4 and 3.2×10¹⁹ m⁻³ respectively, on-axis 900 kW ECRH and D₂ puffing were considered. The model proved to describe rather fast penetration of the density disturbance from the edge to the core during 15…20 ms after gas puffing. The simulation of the density profiles agrees with experiment in Ohmic and ECRH phases, and during the gas puffing, describing the particle pump-out after ECRH switch-on. The neutral influx at the plasma edge increases after ECRH switch-on in agreement with Da measurements. Both the effective diffusion coefficient and pinch velocity decrease slightly when the plasma density is increased. A set of two Ohmic and three NBI MAST pulses were considered for comparison

Aerodynamic investigations of ventilated brake discs.

The heat dissipation and performance of a ventilated brake disc strongly depends on the aerodynamic characteristics of the flow through the rotor passages. The aim of this investigation was to provide an improved understanding of ventilated brake rotor flow phenomena, with a view to improving heat dissipation, as well as providing a measurement data set for validation of computational fluid dynamics methods. The flow fields at the exit of four different brake rotor geometries, rotated in free air, were measured using a five-hole pressure probe and a hot-wire anemometry system. The principal measurements were taken using two-component hot-wire techniques and were used to determine mean and unsteady flow characteristics at the exit of the brake rotors. Using phase-locked data processing, it was possible to reveal the spatial and temporal flow variation within individual rotor passages. The effects of disc geometry and rotational speed on the mean flow, passage turbulence intensity, and mass flow were determined. The rotor exit jet and wake flow were clearly observed as characterized by the passage geometry as well as definite regions of high and low turbulence. The aerodynamic flow characteristics were found to be reasonably independent of rotational speed but highly dependent upon rotor geometry

Self-organization of hot plasmas: the canonical profile transport model

In this monograph the author presents the Canonical Profile Transport Model or CPTM as a rather general mathematical framework to simulate plasma discharges.The description of hot plasmas in a magnetic fusion device is a very challenging task and many plasma properties still lack a physical explanation. One important property is plasma self-organization.It is very well known from experiments that the radial profile of the plasma pressure and temperature remains rather unaffected by changes of the deposited power or plasma density. The attractiveness of the CPTM is that it includes the effect