THERMAL RADIATION AND ITS EFFECTS （热辐射及其影响）.pdf

CHAPTER VII THERMAL RADIATION AND ITS EFFECTS RADIATION FROM THE FIREBALL GENERAL CHARACTERISTICSOF energy is initially in the form of kinetic THERMAL RADIATION energy of the weapon debris. This ki- netic energy is also absorbed by the air 7.01 One of the important dif- at a slightly later time \(§2.109) and ferences between a nuclear and a con- servesto further heat the air. The heated ventional high-explosive weapon is the air, which constitutes the fireball, in turn large proportion of the energy of a nu- radiates in a spectral region roughly clear explosion which is released in the similar to that of sunlight near the form of thermal (or heat) radiation. Be- earths surface. It is the radiation (ultra- cause of the enormous amount of energy violet, visible, and infrared) from the liberated per unit mass in a nuclear fireball, traveling with the velocity of weapon, very high temperatures are at- light, which constitutes the thermal ra- tained. These are estimated to be several diation at distances from the explosion. tens of million degrees, compared with The time elapsing, therefore, between a few thousand degrees in the case of a the emission of this (secondary) thermal conventional explosion. As a conse- radiation from the fireball and its arrival quence of these high temperatures, at a target miles away, is quite msignif- about 70 to 80 percent of the total en- icant. ergy (excluding the energy of the resid- 7.02 It is desirable to state specific- ual radiation) is released in the form of ally what is meant by