Dynamics and Simulation of Head-Medium Interface in Magnetic Storage Systems

为了分析头-介质界面问题中最受关注的头碰撞现象，实现了精确测量飞头动态特性的实验装置，建立了超细间距飞头动态模拟的分析方法。实验装置：采用新设计的由高刚度空气主轴、空气循环除尘系统和振动控制台组成的实验装置，验证了飞头在0.03 μ m以下的稳定飞行运行。利用基于激光干涉测量的间距测量系统，成功地消除了光束光斑中不需要的干涉条纹和激光输出中的共振噪声，实现了高精度至1或2 nm，最小测量极限为0.03 μ m。解析方法：平均膜厚理论倾向于滑移流态下具有表面粗糙度的气体润滑。推导了一个简单的平均雷诺方程，并通过与实验的比较，证实了该方程在滑移流态下表面粗糙度效应的适用性。用数值方法研究了润滑膜的可压缩性对膜厚平均的影响。推导了含各向异性膜厚随粗糙度方向变化的平均静态和动态润滑方程。求解这些方程可以得到存在于计算机飞头和织构介质之间的润滑膜的动态特性。头部滑块飞过凸起时的瞬态响应表明了粗糙度方向和粗糙度运动的影响。有趣的是，纵向粗糙度有助于降低阻尼系数，并对移动的横向粗糙度产生相反的影响。因此，滑块立即飞过凸起的偏移对于纵向粗糙度是最小的，对于移动横向粗糙度的残余振动阻尼速度是最大的。少

TO analyze the head crash phenomena, which are the most significant concern in the head-medium interface problem, experimental apparatus for accurately measuring flying head dynamic characteristics was realized, and analytic methods which enable to simulate the flying head dynamics in a ultra thin spacing were established.1. Experimental apparatus: Stable flying operation of a flying head down to 0.03 mum was confirmed using newly designed experimental apparatus, which comprises high stiffness air spindle, air circulating dust filtering system and vibration control table. A high accuracy of down to 1 or 2 nm and a minimum measurement limit of 0.03 mum were achieved utilizing spacing measurement system based on laser interferometry which successfully eliminated undesirable interference fringes in beam spot and resonance noise in laser output.2. Analytic method: The average film thickness theory was tended to gas lubrication possessing surface roughness in the slip flow regime. A simplif … More ied averaged Reynolds equation was derived and its applicability to determining the surface roughness effects in the slip flow regime was confirmed through comparing with experiments. The compressibility effects of lubricating films incurring a roughness on film thickness averaging were studied numerically.Averaged static and dynamic lubrication equations were derived in the general form containing anisotropic film thickness dependent on roughness orientation. Solving these equations leads to a presentation of the dynamic characteristics of lubricating films existing between computer flying heads and textured media. Transient responses of head sliders flying over a bump were demonstrated indicating the effects of roughness orientation and roughness movement. It is interesting to note that longitudinal roughness serves to de crease damping coefficients and inversely affects moving transverse roughness. Thus, slider excursion immediately flying over a bump is minimum for longitudinal roughness and the damping speed of residual vibration is maximum for moving transverse roughness. Less