['1', ')', 'have', 'been', 'taken', 'from', 'the', 'measured', 'thermal', 'conductivity', 'of', 'another', 'MSSL', 'heat', 'switch', 'with', 'the', 'same', '1.5', 'mm', 'square', 'cross', 'section', ',', 'a', 'free', 'path', 'length', 'of', '43', 'cm', 'and', 'a', 'RRR', 'of', '20,000', ';', 'it', 'has', 'been', 'observed', 'from', 'experiments', 'conducted', 'at', 'MSSL', 'that', 'there', 'is', 'little', 'change', 'in', 'the', 'thermal', 'performance', 'for', 'tungsten', 'heat', 'switches', 'with', 'a', 'RRR', 'between', '20,000', 'and', '32,000', '(', 'subject', 'of', 'a', 'future', 'publication', ')', 'and', 'therefore', 'the', 'performance', 'of', 'the', '20,000', 'RRR', 'heat', 'switch', 'has', 'been', 'assumed', 'to', 'be', 'a', 'good', 'approximation', '.']