强流脉冲离子束辐照钨靶温度场演化数值研究

Numerical study on evolution of temperature field in tungsten irradiated by high-intensity pulsed ion beam

强流脉冲离子束(HIPIB)使材料表面气化产生喷发等离子体从而进行薄膜生长、纳米粉的制备等工作。金属钨的熔点高,热导性好,是耐高热流密度防护层最可能的材料。为了研究金属钨在高热负荷下的响应,建立了HIPIB辐照钨靶的考虑相变的非线性热力学方程,并采用有限元方法数值求解了靶材辐照后的二维温度场演化问题,得到了钨靶温度场的时空演化规律。当离子束流密度为100 A/cm2时,脉冲结束后束流入射中心表层约0.3μm厚的材料熔化,且熔化是从表面开始的,而后因热传导固化;脉冲结束后开始时靶材表面温度急剧下降,而后变得缓慢,温降的梯度在不同时刻均存在峰值,且随时间增加峰值向纵向深度处移动。

High-intensity pulsed ion beam（HIPIB） can modify the characteristics of materials directly by bombardment the surface.HIPIB can also make the surface materials vaporization to form the eruption of plasma and therefore can be utilized to the growth of thin film and the preparation of nano-powders,etc.Tungsten has high melting point and good thermal conductivity,it is a material of the protective layer to resistant the high heat flux most likely.In order to study the response of tungsten under high heat load,the nonlinear thermodynamics equation considering the phase transition was established to the target irradiated by HIPIB.The evolutions of two-dimensional temperature field of tungsten target irradiated by HIPIB were studied numerically by finite element method.The spatial and temporal evolutions of temperature field of tungsten target were obtained.While the ion beam current density was 100 A/cm2,the surface material in thickness of about 0.3 μm was melted after a pulse at the beam incident center,the melting started from the surface,and then solidified due to heat conduction;the target surface temperature decreases sharply at the initial stage after the end of pulse,then slow down.There exists peak of gradient of temperature at every different time,and it moved vertically inside the target with increasing of time.