The Measurement of Acceleration With a Vacuum Tube

Acceleration can be measured with a vacuum tube conisisting of a fixed cathode and two plates, one on each side of the cathode. The plates arc mounted elastically to deflect in response to acceleration normal to their plane. Displacement of a plate alters the electron current delivered from the cathode to that plate. A tube of this type is described which has a natural frequency of about 800 cycles per second, a flat response for sinusoidal accelerations up to 200 cycles per second, and a linear range of 150g. The output at accelerations of 10g is sufficient to drive a high frequency recording galvanometer directly, without the complications of an amplifier. The pricipal disadvantages of the tube are an unpredictable ``zero drift'' and a ``zero shift,'' following impacts of very short duration.