Basically, the thermal simulations of the electrical discharge plasma-foot point are performed using a uniform distribution with spreading foot radius or point assuming a Gaussian distribution. But it raises the question of whether there are effects that can not be neglected or contrary to these assumptions.
I haven't seen any evidence against this assumption. One can look to craters for answers, but I suspect that the ejection process have much larger influence on the crater shape than current distribution.
Although there is one paper "Molecular dynamics simulation of the material removal mechanism in micro-EDM" that might be of interest. The simulation produced similar crater shape as often observed.
What do you think of the statement that the higher current density in the plasma channel acts on the shell surface of the plasma channel, because in the EDM with needle pulses to the skin effect becomes effective.
It is interesting to note that more than 100 viewers interested by this question, but none expresses his opinion. Especially because quite a lot of work to deal with the simulation of thermally-affected zones.
Most functional relationships between radius change and pulse parameters (pulse energy, pulse duration, current amplitude) are quite good for a limited parameter range. These solutions can be used very rarely for bigger process parameters because the functions rise considerably and no longer correspond with the physical reality. For smaller process parameters is an application to a limited extent, when the process parameters are not used as average values.
The use of a Gaussian distribution of the energy density over the plasma-base point is physically not be explained, because the border area of the plasma channel of the transition zone corresponds to the plasma of gas under pressure. Under certain conditions the process parameters could also be assumed that the maximum of the energy density rather in the edge region (before transition zone), which corresponds rather then an annular source as a point source.
The assumption of constant averaged process parameters could meet only at high pulse energies of a static pulse generator. In this case, no importance is attached to the overshoot in the ignition phase, and assuming that the result of energy is considerably greater.
Why we should consider a change in radius?
Because otherwise very large discrepancies in determining the crater geometry (diameter / depth) arise.
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