The nonrelativistic Gyrotron

Summary form only given. We have theoretically and experimentally studied a nonrelativistic Gyrotron operating at about 2 KV. Although others have discussed the operation of Gyrotrons operating via the relativistic effect at 2 KV¹, they apparently have not considered the consequences of the required residence time of the electrons in the interaction region. At 2 KV, the relativistic frequency shift is 0.2 %, which means to get a 180 degree phase shift to produce complete electron bunching, the electrons must remain in the interaction region for at least 250 orbits. In our case, computer simulation shows that the residence time is on the order of tens of orbits. Thus, another bunching mechanism must be present. If we examine the magnetic field of the Kharkov Nonrelativistic Gyrotron, we note for example that in the emission region, there is a weak magnetic mirror. One characteristic of a magnetic mirror is that the magnetic field increases as the radius from the axis decreases. Thus for an electron orbiting the axis, as the electron loses energy, it decreases in radius, encounters an increased magnetic field, has a higher gyrotron frequency, and moves forward in phase. We now have a negative mass instability. This instability is due to gradients in the magnetic field, not relativistic effects. In conclusion, we have developed both the theory for a low voltage Nonrelativistic Gyrotron, and have constructed and demonstrated a device that works. In addition, we have found a limitation on residence time that makes it difficult for low voltage Gyrotrons to operate successfully via the relativistic effect.