commgrp@silver.bacs.indiana.edu (12/23/88)
>In article <7200022@silver> commgrp@silver.bacs.indiana.edu writes: >>RS catalog # 276-087 "Super-Bright LED" ($1.69, from Japan) is truly >>impressive. It's rated 2000 mcd output at 20mA (red; wavelength 660 >>nm). >Of course, the *REAL* question is: How do they perform when >immersed in liquid nitrogen? >Original LEDs had a significant increase in efficiency when >supercooled... Unfortunately, the high efficiency LEDs (40mcd) I >tried didn't have the same effect. It would be interesting to >know if these new LEDs do. They would be really impressive with >several hundred mA of current at significantly higher efficiency! >--Charles flaig@apple.com Other semiconductors work better at liquid nitrogen temperatures too. I once worked for a manufacturer of silicon rectifiers which made a water-cooled 1000-Amp unit with a single enormous alloyed junction (which couldn't be duplicated when they changed to a diffused-junction process). A cyclotron facility in California got 10,000 Amps through these by cooling with LN2. -- Frank reid@gold.bacs.indiana.edu