Conducted noise reduction via modulating trigger in copper vapour laser

The distinct method of stabilizing the impedance of discharge plasma in copper vapour laser (CVL) by trigger modulation significantly reduced the conducted noise in the system. The level of conducted noise produced by the laser is directly related to the degree of impedance disparity between the laser and the pulse power supply. The intermittent missing of the high voltage discharge pulse applied across the laser head increases the laser impedance due to enhanced time for charge carrier recombination. Experimental research indicates that by missing 0.2% of the high voltage discharge pulse, the conducted noise at the output of the DC supply in the CVL system is reduced by 5dbµV. The conducted noise from the CVL system operated at 9kHz was measured in three different conditions - 1) Without intermittent pulse missing 2) Intermittent pulse missing after every 5 s and 3) Intermittent pulse missing after every 2.5s. This paper presents that besides improving thermal stability and power coupling, the trigger modulation also reduces the electromagnetic interference (EMI) from the CVL system. The technique of mitigating EMI from a gas discharge load by manipulating the plasma impedance can be implemented in other applications that require a decrease in EMI emanating from high-current and high-voltage gas discharges.