A study of ion currents in an oxyfuel flame due to work surface chemical action

Experiments controlling for work surface temperature and chemical activity under an oxyfuel cutting torch flame reveal that ion currents in the flame can double or even triple due to chemical action at the work surface. Steady-state experiments over copper coupons with various diameters at various temperatures are compared against transient experiments over steel plates with various surface conditions. In extreme cases, steel samples are coated with salts, and the effect is exaggerated by an order of magnitude. These measurements demonstrate that there are two sources of ions in the system; the chemical reaction in inner cone and the work surface. A number of plasma properties are estimated from measurements show good agreement with prior measurements in simpler geometries. These form the basis for an argument in favor of a simplified flame model proposed in the conclusions.