Abstract: A tester system includes a tester and a radioactive isotope source. The tester includes a spindle assembly, a disk mounted to the spindle assembly, and a head actuatable over the disk. The radioactive isotope source is positioned in an ionizing location proximate the tester, such that a minimum distance between the radioactive isotope source and an axis of rotation of the disk is less than a radius of the disk.

Abstract: A novel method for defining a touch-down power for a head that has a head-based flying height actuator is disclosed and claimed. A linear relationship between power and spacing is derived by fitting to first and second transducer-disk spacings corresponding to first and second electrical powers applied to the head-based flying height actuator. A third spacing between the transducer and the disk is determined when a greater third electrical power is applied to the flying height actuator. An estimated third spacing between the transducer and the disk, corresponding to application of the third electrical power to the flying height actuator, is calculated using the derived linear relationship and the third electrical power. The touch-down power is defined to be substantially equal to the second electrical power if an error between the third spacing and the estimated third spacing is larger than a first threshold.