Actively cooled SLMS technology for HEL applications

Schafer has demonstrated two different methods for actively cooling our Silicon Lightweight Mirror System (SLMS TM ) technology. Direct internal cooling was accomplished by flowing liquid nitrogen through the continuous open cell core of the SLMS TM mirror. Indirect external cooling was accomplished by flowing liquid nitrogen through a CTE matched Cesic® square-tube manifold that was bonded to the back of the mirror in the center. Testing was done in the small 4- foot thermal/vacuum chamber located at the NASA/MSFC X-Ray Calibration Facility. Seven thermal diodes were located over the front side of the 5 inch diameter mirror and one was placed on the outlet side of the Cesic® manifold. Results indicate that the mirror reaches steady state at 82K in less than four minutes for both cooling methods. The maximum temperature difference of the eight diodes was less than 200 mK when the mirror was internally cooled and covered with MLI to insulate it from the large 300 K aluminum plate that was used to mount it.