  In magnetic fusion experiments, a simple technique to evaluate the heat flux
on first wall components is a key to controlled plasma surface interaction. The
heat flux can be characterized by the peaking factor which is the ratio of the
peak heat flux to the average heat flux. The peaking factor can be calculated
exactly using simple derivations and standard software tools. This analysis is
applied to an Iter class experiment for plasma wall contact during start up
phases at 15 MW, in idealised, realistic and misaligned situations. Even though
the peaking factors are usually above 10, the peak heat load on the wall
remains moderate at a few MW/m${}^2$.
