October 9, 2008

Bomb-Proof Thermometer Created

British scientists say they have designed a high-speed thermometer that can measure the temperature inside explosions without being damaged by the impact.

The scientists at Britain's National Physical Laboratory said conventional thermometers cannot survive the shockwave, heat, snoot and debris produced by an explosion. Conventional thermocouples do not react quickly enough to capture the information.

But the NPL scientists said they have designed a reusable, bomb-proof thermometer to understand the physical and chemical processes that occur during the detonation and expansion phases of an explosion. They described the device as an optical fiber 400 microns across, protected from the blast by a sand-packed steel tube with one open end.

They said the optical fiber probe collects thermal radiation, which is transmitted to the main instrumentation located at a safe distance.

"We produced a working prototype thermometer after some successful field trials and hope to measure the temperature of full-scale explosions in the near future," the scientists said. "The lab tests involved temperatures of over 3000 kelvin (about 5,000 Fahrenheit) and the only damage done was a small amount soot off the end of the optic fiber, which we easily removed with alcohol and a cotton bud."