Possible ways to increase the efficiency of a low-pressure water vapour discharge as a light source

Methods to increase the efficiency of a rare gas–water vapour plasma as a light source are presented: (1) the addition of a second rare gas (2) the use of titanium dioxide to enhance the decomposition of water molecules into hydroxyl and hydrogen; (3) pulse discharge operation to improve the efficiency. Analysis shows that the first two methods can yield an increase in efficiency. Use of the catalyst produced a tangible impact on plasma properties and an increase in efficiency that was experimentally observed and agrees with theoretical estimates. In pulse discharge operation, negative ions that are probably created in the afterglow phase eliminate the desired effect. The data obtained using these three approaches, point towards possible directions for further investigation and predict the expected results in case of successful implementation.