Numerical investigation of time-dependent electrode-plasma interaction in commercial HID lamps

High-intensity discharge (HID) lamps capture more and more the markets for automotive headlight lamps (D2 lamp), video projection (UHP lamp), street/industrial lighting, floodlighting, etc. They are normally very small (typically 0.7-10 turn electrode gap) and have short time scales, leading to difficulties during experimental investigations. Thus, numerical simulations of HID lamps are an important tool to understand, improve, and develop new HID lamps. Especially the interaction between electrodes and plasma is a very localized and fast process, still not understood satisfactorily. Lamps are usually operated on alternating current (ac); the electrodes switch alternately from anode to cathode phase. Therefore, time dependent simulations that include realistic anode and cathode models are essential. We present a model having the ability to address all these challenges.