ELECTRODE-LESS UV LAMP ON THE BASIS OF LOW-PRESSURE MERCURY DISCHARGE IN A CLOSED NON-FERRITE TUBE

Experimental study of characteristics of a non-ferrite electrode-less UV lamp with a length of 500 mm and width of 130 mm in the form of a closed quartz discharge tube with an inner diameter of 25 mm was conducted. The induction discharge was excited at a frequency of 1.7 MHz within the discharge lamp power P-pl ranging between 52 and 112 W in a mixture of mercury (similar to 10(-2) mm Hg) and argon (1.0 mm Hg) vapours by means of a 3-coil inductance located along the inner perimeter of the closed tube. With P-pl increasing: a) loss power in the inductance wire first decreased from 37 down to 22 W (P-pl = 84 W) and then increased up to 44 W; 2) the UV radiant flux of the lamp in a mercury light-band of 54 nm increased from 28 to 72 W; 3) radiant efficiency of the lamp at the light-band of 254 nm first increased from 31 to 48.5 % (P-pl = 84 W) and then slightly decreased down to 46 %; 4) radiant efficiency of the discharge plasma at the wavelength of 254 nm increased from 53 % to 65 %.