Eye in the firestorm

UK engineers have developed a thermometer that will carefully monitor the extremes of temperature in previously uncharted territory: the fiery heart of a bomb-explosion.

The re-usable device, pioneered by engineers at the National Physical Laboratory (NPL) for the government's Defence Science and Technology Laboratory (DSTL) is expected to provide enormous improvements to the understanding of explosions.

Capable of withstanding the shock, intense heat and soot of a fireball while taking split-second measurements of the temperature at its core, the fibreoptic radiation probe could be used in everything from the development of new bomb-proof materials, to the forensic study of explosions.

To understand bomb-blasts at present, scientists use computational fluid dynamics (CFD) computer simulation techniques. Data relating to the size of a simulated explosion is entered into a computer and the simulation is run. The problem is that typically this relies on a little bit of guesswork as there is no reliable technique for measuring one of the key parameters — the temperature at the heart of the blast.

Gavin Sutton, the NPL scientist behind the development, explained that DSTL wanted a way of acquiring this data so it could improve the realism of its computer simulations.

'There's very little data regarding the conditions at the centre of an explosion,' he said. 'DSTL wanted to make sure that temperature of an explosion was getting to a particular level and they wanted it to augment CFD simulations.'

While this is not the first effort to take a peek at the temperature inside an explosion it is certainly the most promising. In the past scientists have attempted to use a variety of techniques. These include the use of thermocouples, which do not respond quickly enough, and optical thermometers, known as pyrometers, which have been used to probe explosions from a distance. 'But no-one,' said Sutton, 'has ever stuck something directly inside a fireball — it's uncharted territory.'