Numerical Research On Temperature Field Of The Ablation Of GaAs Bombarded By Intense Pulsed Ion Beam

In the last 20 years,because of being have many advantages for intense pulsed ion beam (IPIB),it has been extensively applied in the material science and engineering field for different motivation for the different effects of the interaction between target and beams with different energy densities.With different energy densities,IPIB has been used for different motivations.Such as for higher one,it can be used to modify materials,deposit film and produce nano-size powder.Therefore how to accurately control the parameters of IPIB to realize different purposes is an important issue.It is not enough to decide what the parameters of IPIB should be used by experience.So it is necessary to establish the executing method numerically to deal with the nonlinear problem.The numerical simulation was completed according to a fitting result from the waves of the ion diode magnetically insulated and the ion current density detected by Faraday cup at the focus region of the Russian TEMP type accelerator imported from Russia.Many problems have been discussed,such as energy threshold quantity of melt,vaporization and the evolution of temperature field problems during the irradiation period of GaAs target by IPIB.A one-dimensional model on the evolution of the distribution of the temperature in the target bombarded by IPIB is given based on energy equation according to a fitting result from the waves of the ion diode magnetically and the ion current density detected by Faraday cup at the focus region.In our numerical simulation,we assume the IPIB with pulsed width 70ns,fit pulsed voltage profile with maximum peak value 300kV,the density of ion beam with average value 180 A/cm~2 and power density curve.For the ion beam of H~+ 70%,C~+ 30% bombarding the GaAs target vertically,the depth of the deposited energy is 2.75 microns depth and the maximum surface deposited energy is 18.2kJ/cm.These numerical simulations reveal the temperature distributing in the GaAs target,which provides quantitative information of melting threshold quantity(2.59kJ/cm) and melt happens at the first 10ns of a pulse.The simulative results are close to experimental parameters.Different ratio of ions has different impacting on GaAs target by IPIB.Using graphite anode or polyethylene coating of MID of the accelerator have been researched:the range of carbon ion is shorter and the range of proton is longer,therefore the energy of beam produced by MID with graphite anode(H~+ 30%,C~+ 70%)mainly deposits on the surface layer,it is adapt to deposit film;but for the beam produced by MID with polyethylene coating(H~+ 70%,C~+ 30%),the energy mainly deposits in the deeper layer of target,it is adapt to modify materials.