Investigation of Pulsed Mode Operation in Low-Temperature Arsenic Plasma Light Sources

Arsenic high-frequency electrodeless discharge lamps, used as photonic devices, have been previously explored for application in atomic absorption spectrometry to detect arsenic in the environment at low concentrations. Such lamps are known for their stability and long lifespan, providing narrow spectral lines necessary for atomic absorption spectrometry. In addition, arsenic discharge lamps have potential applications in disinfection with similar or even better effectiveness than typically applied mercury-containing lamps. However, under certain preparation and working conditions, arsenic lamps may begin to operate in a pulsed mode. The reasons for this phenomenon are still not fully understood. In this study, we investigate the behavior and temperature of arsenic lamps in the pulsed mode regime. Low temperature inductively coupled arsenic plasma was created using an outer electromagnetic field of 300 MHz. The typical excitation voltage was set by a high-frequency generator within the range of 17-19~V. The temperature fluctuations of the lamp during pulses were monitored using an infrared camera. Our results showed that the repetition rate of pulses was higher for higher operation voltages and was in the range of 20 to 60 seconds. The temperature changes during pulses were in the range of 300-400°C. Radial variation of temperature distribution was also detected.