Reversibility and the Damping of a Double Beam Instability

An experimental and theoretical investigation has been made of the absolute instability that occurs near $\frac{1}{2}{\omega }_c$ when two opposing drifting electron beams interpenetrate in a static magnetic field. The theory allows determination of the beam temperature by measurement of cutoff magnetic field or cutoff beam velocity. The result of the measurement is that the beam temperature is equal to the cathode temperature and we conclude that no irreversible change takes place.