DEVELOPMENT OF A PASSIVE THERMAL ATTENUATOR (PTA) WITH DIODE-LIKE THERMAL RESISTANCE CHARACTERISTICS

CERTAIN SUBSTANCES EXHIBIT NONLINEAR RESPONSES TO THERMAL GRADIENTS APPLIED ACROSS THEM. IN PARTICULAR, CERTAIN COMPOUNDS OF THE IIIA/VA GROUPS EXHIBIT UNIDIRECTIONAL RESPONSES TO THERMAL FLUX, WHERE THE CTE DIFFERS BETWEEN XAND Y-, OR XAND ZAXES. WE PROPOSE TO USE A COMPOSITE MATRIX OF TWO DIFFERENT MATERIALS SANDWICHED INTO A SMALL CROSS-SECTIONAL AREA, TO ACT AGAINST THE NORMAL THERMAL GRADIENT. THE MATERIALS DIFFER SUBSTANTIALLY IN THEIR CTES, ONE HAVING NEARZERO OR NEGATIVE CTE, THE OTHER EXHIBITING NORMAL, POSITIVE, BUT LINEAR CTE. BY CAREFUL GEOMETRIC INTERDIGITIZATION BETWEEN FINGERS POF ZERO/NEGATIVE-CTE MATERIAL AND UNIDIRECTIONAL-CTE MATERIAL, A COMPOSITE CAN BE CONSTRUCTED WHICH ACTS LIKE A HIGH-EFFICIENCY THERMALCONDUCTOR WHEN THE FLUX IS APPLIED FROM ONE SIDE, AND ACTS LIKE A THERMAL BARRIER WHEN THE FLUX IS APPLIED FROM THE OTHER SIDE. COMPOUNDS IN THE BORON NITRIDE CATEGORY HAVE BEEN TARGETED AS OFFERING DESIRABLE CHARACTERISTICS FOR SUCH A DIODE-LIKE DEVICE. RESEARCH WILL BE CONDUCTED INTO THE USE OF BORON NITRIDE AND SIMILAR COMPOUNDS IN THE CONSTRUCTION OF SUCH A PASSIVE THERMAL ATTENUATOR (PTA).