Volatilization rate of free particles in a d.c. arc plasma,burning in air under atmospheric pressure

The volatilization rate (Q) of free particles (atom, ions and molecules) from the anode cavity into the discharge zone of d.c. arcs burning in air under atmospheric pressure was studied. In volatilization rate of particles of uranium, thorium and zirconium matrices was measured by two methods. The first is an indirect method, in which the residue in the anode cavity after the arcing period was chemically analysed (Q_ch and corrections for side losses of particles were applied. The second method is a direct one, in which aluminium wires were passed at uniform velocity through the plasma, in the vicinity of the anode. The wires coated by the free particles were analysed (Q_w) by neutron activation for uranium and spectrochemically for thorium and zirconium content. The two methods are compared.