Modeling the Variation in Properties Arc Discharge With Varying Metal Halide Concentration and Voltage at Atmospheric Pressure

ABSTRACT This simulation‐based study investigates the effects of dysprosium triiodide (DyI 3 ) addition and the applied voltage U on the electrical, thermal, and ionization characteristics of an arc discharge at 1 bar. The main objective is to evaluate how DyI 3 concentration and control of near cathode voltage drop influence plasma cathode coupling, which may contribute to maintaining stable lamp operation and extending the operational lifetime of the lamp. Pure Hg and Hg‐DyI 3 mixtures containing (0.1, 1, and 10) mol% DyI 3 were simulated using the NCPL model. The cathode surface temperature T w ranged from 1000 to 5000 K, and U was set at 20 and 60 V. The analysis focused on the energy flux density transferred from the plasma to the cathode q p , electron temperature T e , and ionization degree ω. The magnetic flux density B was also estimated from the total current density j using Ampere's law. The results show that increasing U from 20 to 60 V produces the strongest changes in the near cathode plasma properties. At U = 60 V, U D decreased from about 58–59 V at low T w to 35–37 V at T w = 5000 K, while U i increased to about 23–25 V. Increasing U from 20 to 60 V shifted the onset of ω ≈ 1 from about 3650 to 3300 K. These findings demonstrate that DyI 3 addition and voltage control significantly affect energy transfer, ionization, and plasma cathode coupling, supporting the optimization of mercury metal halide arc lamps.