Pulsed spherical probe measurements in flames

Measurements in a propane-air flame show that the falloff of probe current following the application of a negative pulse to a spherical probe is approximately given by Ii=2π(ε0µene)^1/2rpVpt^-1/2where Ii=probe current, ε0=permitivity of free space, µ=ionic mobility, e= electronic charge, ne=electron density, rp=probe radius, Vp=amplitude of pulse,and t=time.