| Popis: |
The effect the high-frequency field frequency and lamp design parameters have on the performance characteristics of the inductor of a ferrite-free inductively-coupled closed-loop tube is studied within the framework of a transformer model. The discharge was excided in tubes with diameters equal to 16, 25 and 38 mm in a mixture of mercury vapour (~ 0.01 mm Hg) and argon (0.6 mm Hg) at driving frequencies equal to 1.7, 3.4 and 8.5 MHz and plasma power equal to 25–200 W by means of an induction coil containing 1, 2 and 3 turns, and placed over the closed-loop tube inner perimeter. It has been found that the dependences of inductor high-frequency current and voltage, and power loss in the coil wire on the discharge plasma power have a minimum, which shifts toward lower power levels with increasing the driving frequency and discharge tube diameter. The minimal values of coil current, voltage, and power losses decrease with increasing the driving frequency, tube diameter and number of coil turns. The prediction results are in satisfactory qualitative agreement with the experimental data; the mismatches are supposedly due to the assumptions adopted in the model, according to which the skin effect and electric field spatial inhomogeneity were not taken into account. |
