  The distribution of particles and power to plasma-facing components is of key
importance in the design of next-generation fusion devices. Power and particle
decay lengths have been measured in a number of MAST L-mode and H-mode
discharges in order to determine their parametric dependencies, by fitting
power and particle flux profiles measured by divertor Langmuir probes, to a
convolution of an exponential decay and a Gaussian function. In all discharges
analysed, it is found that exponential decay lengths mapped to the midplane are
mostly dependent on separatrix electron density and plasma current (or parallel
connection length). The widths of the convolved Gaussian functions have been
used to derive an approximate diffusion coefficient, which is found to vary
from 1m2/s to 7m2/s, and is systematically lower in H-mode compared with
L-mode.
