Presence Of Mechanical Vibrations Research Articles

Measurement of electron density gradients using a modified Jamin interferometer

The use of a modified Jamin interferometer for the measurement of electron density gradients in a transient plasma has been demonstrated using a small Z pinch argon discharge. The interferometer was operated with 632.8 nm radiation from a He-Ne laser, and an interference pattern was produced using wedge shaped plates. With both beams of the interferometer passing along the length of the plasma and separated by 3.8 mm, differences in electron density were measured, and hence radial electron density gradients were derived. Electron density gradients as small as 5*1022 m-4 could be detected with good reproducibility. The Jamin interferometer used in this way was found to have several practical advantages over the Michelson and Mach-Zehnder interferometers, even for absolute electron density measurement. These advantages include simple alignment, fewer optical components, and a stable, easily viewed interference pattern even in the presence of mechanical vibration. The interferometer was also used to locate the position of the centre of the Z pinch discharge to within 0.2 mm.

The effect of heat treatment on magnetoelastic lossess and losses of a nonmagnetic nature in 30KhGSA steel in the presence of mechanical vibrations

1. The level of damping in hardened and low-temperature (up to 400°C) annealed 30KhGSA steel subjected to large stresses (τ>10 kgf/mm2) is determined mainly by the losses of a nonmagnetic nature, and following tempering at temperatures above 400°C, by the losses due to magnetoelastic hysteresis. The relative contribution of magnetoelastic damping at high τ values to the total level of damping is calculated for this particular steel following various heat treatments. 2. Damping of a nonmagnetic nature δc diminishes with tempering temperature rising to 400°C, while above this temperature δc is almost constant. The increased damping at high τ values, as the result of tempering at 520 and 600°C and after normalizing, is due to the increased magnetoelastic hysteresis losses. 3. A relationship is established between damping characteristics (δ, δm, δc), hardness, and magnetic properties of this particular steel.