Research On The Energy Deposition Of X-rays And Characteristic Of Thermal Radiation In The High Altitude Nuclear Detonation

High Altitude Nuclear Detonation(HAND)generally refers to the nuclear explosion with explosion height above 30 km.The energy of X-rays accounts for 70%-85%in HAND,which is one of the main damage factors and the source of the fireball phenomenon of nuclear explosion.Due to the thin atmosphere and long X-rays free path at high altitude,a large range of air could be heated by X-rays around the explosion point.Then the energy deposition make the temperature of air rises to form a fireball,and the fireball produce strong infrared radiation,forming a large range of light curtain in space.Thus HAND could cause the unique optical phenomenon and damage effects other than low-altitude nuclear explosions.Based on the theory of interaction between photons and matter and the theory of radiation fluid mechanics,this paper studies the energy deposition process of X-ray generated by high altitude nuclear explosion in the atmosphere,the evolution process of X-ray fireball and combustion fireball formed by the rise of air temperature,and the thermal radiation characteristics.The main works are as follows:1.Starting from X-rays point source,we study the interaction between X-rays photons and air atoms in two-dimensional spherical coordinates.And we write the X-rays energy deposition program based on the equivalent absorption coefficient physic model in the high-altitude atmosphere.Then we used it to calculate the absorption of X-rays photons with different energy accurately in the two-dimensional spherical coordinate system.Finally,we obtain the X-rays energy fluences and energy depo- sition at different inclination angles or explosion heights in the nuclear explosion.2.The energy of X-rays produced by nuclear explosion could be converted into the internal energy of the atmosphere by means of heat air.By studying atmospheric state equation in the high-temperature and low-density condition,the distribution of initial temperature of the X-rays fireball is obtained if the radiation is ignored during process of heating atmosphere.3.The X-rays fireball is used as the initial condition for calculating the evolution of the combustion fireball.In the thin medium,the radiation migration equation is solved by radiation approximation.The temperature,shape,and radiation properties of the combustion fireball during the cooling phase are obtained.Therefore,we could make a preliminary assessment of impact time and range of high-altitude nuclear explosion on infrared detection equipment.