Ferrite-Free Closed-Loop 13,56 Mhz Inductively- Coupled Low Mercury Pressure UV Lamp

Abstract

Electrical and radiation characteristics of inductively-coupled ferrite-free low mercury pressure discharges exited at a frequency of 13.56 MHz and discharge plasma power, Ppl = (5 ? 300) W, in closed-loop quartz tubes of 815 mm in length and of 16.6 mm in diameter were experimentally stud-ied. Discharges were excited and maintained with the help of one-turn induction coil made from litz wire and disposed on the tube wall surface along tube perimeter. Tubes were filled with mercury vapour (~ 10Ц2 Torr) and argon (0.5, 0.7, 1.0, and 2.0) Torr. As discharge plasma power, Ppl, were increased from 130 W to 275 W, coil resonant frequency (RF) voltage grew from (560 ? 700) V up to (840 ? 860) V, RF coil current grew from (1.4 ? 1.8) A up to (2.4 ? 2.6) ј. Coil power losses was highest in the lamp with argon pressure of 0.5 Torr and grew from 30 W (Ppl = 150 W) to 70 W (Ppl = 230 W). UV resonant (254 nm) radiation flux grew with plasma power and was highest in the lamp (pAr = 0.5 Tоrr) while UV radiation generation ef-ficiency of this lamp had maximal value of 34 % at plasma power of 130 W.