On Electromagnetic Measurements of Particle Velocity

Abstract

One of the shortcomings of the classical electromagnetic method of Zavoisky is sensitivity to the non-one-dimensionality of the flow behind the wave front. In this paper, it is proposed to use a four-pin gauge to correct measurements. Two signals are recorded from \(\Pi\)-shaped gauges, one of which is located in a plane tangent to the front, and the other in a plane parallel to the direction of wave propagation. Next, the two signals are combined into a true velocity signal that is insensitive to the curvature of the front. The second difficulty that arises in electromagnetic measurements is the rather large size of the gauges. Typically, the length of the working arm \(L\) is about 1 cm. An analysis of the potential distribution in the gauge shows that the proposed combined gauge is equivalent to two sensors of zero width, and the effective length \(L\) is the distance between the midlines of the leads. It is shown that the value of \(L\) can be reduced to 1.5–2 mm with a lead width of about 0.5 mm. This makes it possible to perform local measurements at spots of millimeter size and use small-size charges. These improvements bring electromagnetic measurements closer to the level of modern optical techniques while using much cheaper equipment.