Downloaded from https://www.everyspec.com MIL-STD-81OC periods For the periods of lamp or electrode replacement must be considered. present, it appears appropriate to merely state that the of fluctuationmust be considerably less than the time constant of the test area of interest. 3. Spectral distribution shall be measured at a carefully defined point in the beam. The bandwidth shall be no longer than that indicated in table 517.2-IV. Bandwidths of 500 Angstrom are preferable.
The total area under the spectral curve shall be normalized to 1353 w/m2 for comparison with the Johnson Spectral Curve having equivalent units, The accuracy shall be the smallest number in the applicable level of table 517.2-V. Calibration of spectral measuring equipment shall conform to current NBS recommendedpractices. If some other means of measuring spectral distribution should be used as a multiple filter radiometer, then proof of its calibration source through use of accurate measurements with shall be furnished. against ~he same a monochromator 4. PROCEDURES 4.1 Procedure IF solar simu%aeien.
The test item shall be subjected to a pressure of 10-> Torr or lower in order to virtually eliminate heat transfer by convection. The test item shall initially see black coated chamber walls maintained at 100”K in order to simulate the heat sink of space, Simulated solar radiation shal1 be applied to the test item from the direction correspondingto that of the Sun in space. The test object shall be mounted in the test chamber (Apparatus2.1) having a cryogenic heat sink (Apparatus2.3) and a solar simulator (Apparatus2.2.1). The specimen shall be installed in the test volume on a fixture supported by low heat conduction means.
If orbital simulation is required, the fixture shall provide means of motion. Albedo and planetary radiation may be simulated by the use of heat flux sources (Apparatus2.2.2). Recommended parameters for specific solar test requirements are specified in table S17.2-VI. METHOD 517.2 517.2-8