On radiant energy in high-temperature research

The mechanism of heating solids with radiant energy is reviewed and the need for measuring radiative properties is pointed out. Image furnaces are suitable for such measurement at high temperatures. The limitations of image furnace operations are discussed and methods as well as equipment offered to overcome the limitations. The importance of artificial black bodies in high-flux measurements is described and a new shape for such cavities is proposed. Data comparing this shape with hitherto used shapes are tabulated. Design for a fast-action on-off shutter for image furnaces is presented. In its retracted position the shutter does not cast any shadow on the mirror and it does not require artificial cooling even when exposed to radiation.