The apparatus of the present invention provides for the dual use of a UV source to heat a substrate and to facilitate photochemistry necessary for the treatment of the substrate. The plasma processing apparatus includes a refrigerant channel for circulating a refrigerant formed in a shower head, thereby easily controlling the temperature of the shower head and improving the reproducibility of plasma treatment. This lighting control system enables the lighting load performing two-level or multi-level illumination in a simple and power saving manner. This is particularly favorable in the case of twin-engine commercial aircraft that are used on short hauls.