A study of GMR read sensor induced by soft ESD using Magnetoresistive Sensitivity Mapping (MSM)
Electrostatic discharge (ESD) can be manifest on giant magnetoresistive (GMR) head either physically (melting of sensor element) or magnetically (degrades in dynamic electrical or quasitest parameters). The latter case is usually suspected as ldquosoftrdquo ESD and known to be a subtle case for study. In this study, we try to differentiate the ldquosoftrdquo ESD from electrical failure, which cause by other means. Ahead with magnetoresistance sensitivity mapping (MSM), which is an additional feature of magnetic force microscope (MFM), the symmetry and sensitivity changes of GMR sensors were further investigated. Advanced analytical tools of atomic force microscope (AFM), MFM and MSM allow unique characterization of head microstructure, and coupled with methodical and systematic failure analysis, may be possible to observe in-situ the previously unknown ESD phenomena unique to GMR head.
Correlation of magnetoresistive sensitivity mapping (MSM) with spin stand performance
Magnetoresistive sensitivity mapping (MSM) uses an AFM tip coated with a hard magnetic film as a flux source to provide a read sensitivity profile on a biased MR head. The resulting MSM signal is monitored using a modified electronics package attached to a standard probe microscope. MSM scans are compared with standard trackscans and /spl mu/-tracks of the same heads and are shown to detect the same anomalies in the read sensitivity profile.
HYPERGOLIC REACTION MECHANISMS OF CATALYTICALLY PROMOTED FUELS WITH ROCKET GRADE HYDROGEN PEROXIDE
Abstract The coupling of the physical and chemical processes controlling the ignition delays (τ ign ) of hypergolic propellants complicates the direct analysis of the transient ignition processes. The transport properties of both the propellants and the ambient gas, and the heat of vaporization and reaction affect τ ign and must be considered experimentally. Furthermore, since hypergolic ignition occurs, by definition, on contact, the mechanics of initial contact and subsequent mixing can affect τ ign and must also be considered. Experimental results from a study of the hypergolic ignition of a catalytically promoted fuel with rocket grade hydrogen peroxide (RGHP) are presented. Statistical analysis of the experimental data was conducted to evaluate the relative effects of RGHP concentration, initial ambient pressure, and the ambient gas on τ ign . At RGHP concentrations of less than 92% in water, stable ignition was difficult to achieve. At sufficiently high Lewis number, an oscillatory ignition process is observed. A phenomenological model comprising mixing, RGHP decomposition, fuel heating and vaporization, and auto-ignition is presented and compared to the experimental results.