Tape dynamics in a high-speed helical recorder

Tape dynamics in a helical recorder were measured at head speeds up to 75 m/s. The onset and amplitude of transverse waves are studied as a function of head velocity, tape tension, and tape thickness. Wave patterns are plotted over a range of these parameters. The tape deflection directly behind the head, in front of the head, and at the tape edge is investigated and compared to theoretical predictions of tape deflections reported in the literature. For the range of parameters studied, damping of tape dynamics was increased in cases with lower head velocity, higher tape tension, and thinner tape. Chevron-shaped wave patterns were found to wrap around the head. The general deflection of the waves, particularly the short waves preceding the head and the dip trailing the head, correlate well with predictions existing in the literature. However, the chevron-shaped wave pattern that extends to the tape edges at high head speeds has not been predicted in the literature. The present measurements indicate that free tape-edge boundary conditions should be assumed in a high-speed model, and that the tape behavior in the vicinity of the head is a strong function of head speed, tape tension, and tape thickness.<
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