On the energy balance in the core of electrode-stabilized high-pressure mercury discharges

Abstract

In a 3.7 MPa electrode-stabilized high-pressure mercury discharge the temperature profile is determined by emission coefficient measurements of the 577 nm mercury line. Values of the net-emission Ue as radiation loss per unit volume are derived assuming the electric field strength decreases with increasing distance from the arc axis. The results can be fitted by an expression of the form ue approximately p exp(-E/kT) where p is the pressure, and E=7.5 eV is an average excitation energy. The numerical value of E is in satisfactory agreement with earlier determinations of this quantity. The model calculations show that there is no significant current dependence of the axis temperature at currents above 1 A but that there is a strong correlation between the axis temperature and the field strength.