固体激光器中多块热沉夹持晶体散热时接触热导研究

Research on Thermal Contact Conductance Using Multi-Piece Heat Sink to Hold Crystal and Dissipate Heat in Solid-State Laser

采用圆棒状工作物质的固体激光器中,通常用2块带有半圆型凹槽的金属热沉夹持晶体散热。装配压强在晶体与热沉接触面上的不均匀分布,造成二者间接触热导沿圆周变化,在晶体中产生非轴对称的温度分布。提出采用3块或4块热沉夹持圆棒晶体散热,利用截断高斯模型和塑性形变模型计算晶体与热沉间接触热导,建立了接触散热模型,并用有限元法得到晶体温度分布。结果表明,2块热沉夹持圆棒晶体散热时,晶体侧面压强、接触热导沿圆周变化明显,在热沉凹槽底部达到最大,在2块热沉结合面处为零,晶体端面温度沿周向变化较大。采用3块热沉时,晶体侧面压强、接触热导及温度分布的周向均匀性提高,端面中心温度降低,采用4块热沉时,晶体侧面压强、接触热导及温度分布的周向均匀性最好,端面中心温度最低。

A pair of metal heat sinks with half-round groove is always used to hold the crystal rod and dissipate heat in solid-state lasers working with round-rod material. The nonuniformly distributing of assembling pressure on the contact surfaces of the crystal rod and heat sinks makes the thermal contact conductance change along the circumference direction, and causes distribution of temperature inside the crystal rod non-axisymmetric. Two methods of using three or four heat sinks to hold the crystal rod are presented. The relationship between thermal contact conductance and assembly pressure is discussed using the truncated-Gaussian model and the plastic- deformation model. Distributions of the temperature inside the crystal are obtained by the finite element method based on the contact heat-dissipating model. The results show that the pressure and the thermal contact conductance on the side-face of the crystal change obviously along the circumference direction when using a pair of metal heat sinks, which reach maximum in the bottoms of the sink grooves and minimum in the joining directions of the surfaces of heat sinks. And the end-face temperature of the crystal changes largely along the circumference direction. In the method of using three heat sinks, the uniformity of pressure, thermal contact conductance and temperature distribution inside the crystal are greatly improved, and central value of the end-face temperature is reduced. When using four heat sinks, the result is the best and the central end-face temperature is the lowest.