Light emission of metal halide lamps under micro- and hypergravity conditions

The wavelength-integrated light output from a metal halide discharge lamp is measured for gravity conditions varying from 0to1.8g during parabolic flights. The results show that the changing gravity affects the convection flow in the lamp, which in turn changes the total light output. For vertically burning lamps, the sign and magnitude of the effect can be predicted using the demixing parameter: the ratio of typical diffusion to convection times. In horizontally burning lamps at 0g, the absence of convective mixing results in a reduced light emission.