High UV (λ≥2200 Å), visible, and near infrared (λ≤0.8 μm) transmissive liquid coolant for high power microwave (2.45 GHz) plasma tubes

摘要: Commercially available dimethyl polysiloxane is shown to be an excellent liquid coolant for the containing walls of high power plasmas (≥300 W/cm3) excited with 2.45‐GHz microwaves. This stable, nontoxic, and nonflammable fluid has very low microwave absorption (tan δ=e‘/e’=3.5×10−4) at this frequency. Fortuitously, it also ultraviolet, visible, near infrared (λ≤0.8 μm) transmission. The UV transmission over 1 cm shows 2% 2000 A, a 30% 2200 80% 2400 100% λ≳2500 A. These features plus its good physical (viscosity, thermal conductivity, specific heat capacity, vaporization, density) electrical (resistivity breakdown) properties make unique as emitting plasma lamps. clear coolant’s λ≥1.0 μm reduces radiative (heat) emission from plasma. In addition, wide operating temperature range, −73 °C≤T≤260 °C. Particular proc...