Abstract. Experimental prototypes of the high-voltage power sources for initialization of a gas discharge in the channel with boiling liquid are designed. The development principle of the device for control of the discharge system parameters is presented. The emission characteristics of a gas discharge at different frequencies are given.
IntroductionToday there is an intensive development of devices for water composition analysis [1]. Designed devices vary in the studied parameters, dimensions and price. Special attention is paid to a compact device capable of analyzing an aqueous solution sample in the field conditions. The gas discharge at atmospheric pressure is often used for this purpose [2,3]. This type of discharge has high temperature and pressure plasma, which serves as a high brightness light source. If liquid is placed between the electrodes and the discharge is initiated, the spectral lines of chemical elements which salts are dissolved in the liquid will arise in the spectrogram, saying about the qualitative composition of the analyte under study [4,5].In this regard, when creating devices for gas discharge initialization in the field conditions, a number of problems should be solved, related not only to the choice of the discharge cell, but also to the development of an electrical circuit for excitation and control of discharge parameters. Currently there are a number of systems that are intensively used to maintain the gas discharge at atmospheric pressure that do not require high voltages and frequencies of the power source. There are three types of these devices of frequent occurrence: a system with a liquid electrode, a system with a liquid supply and a system with boiling liquid in a channel. Each of them has a number of advantages and disadvantages. The system with liquid supply is used in industrial enterprises, has a complex structure and is inefficient in the analysis for small samples. The system with a liquid electrode has simple structure, but it is quite difficult to ensure the safety of the spectral lines registration in this case, because the optical fiber should be placed quite close to the discharge arc. The most safe and easy to use is a system with boiling in the channel which is shown in figure 1. The electrodes 2 are located in the vessels 1, interconnected by a quartz glass capillary 3.To excite and maintain the gas discharge in this system the high-voltage pulse power sources capable of providing the output voltage up to 5 kV and pulse repetition rate in the range from 15 to 50 kHz should be used. These settings should be maintained in the specified ranges to ensure optimal initialization conditions in a portable device. In order to simplify the actions of the intended user, the
