Linear Stability of Relativistic Space-Charge Flow in a Magnetically Insulated Transmission Line Oscillator
Abstract
The magnetically insulated transmission line oscillator (MILO) is a high-power microwave device that combines the technologies of magnetically insulated electron flow and slow wave tubes. This combination makes the MILO a unique and robust device capable of operation over a wide range of voltages. MILOs are linear, two-conductor systems comprised of a cathode and an anode. The cathode is a smooth conductor. The anode consists of periodically spaced cavities. The system forms a slow wave transmission line capable of transmitting electromagnetic waves having phase velocities less than the speed of light (slow waves). MILO operation is initiated by charging the cathode to high voltage with respect to the anode. The large electric field on the cathode surface generates a plasma from which electrons are emitted. For sufficiently high voltage, the electrons are magnetically insulated from the anode and drift down the transmission line with substantial kinetic energy. A microwave generating instability occurs when the slow electromagnetic wave phase velocity is slightly less than the electron drift velocity when wave amplification occurs at the expense of electron energy. The dispersion relation is obtained by applying linear perturbation theory to Maxwell's equations coupled to equations for the electron equilibrium. Two models are used for the electron equilibrium: (1) thin-beam, and (2) relativistic Brillouin flow. The dispersion relation is numerically solved to obtain oscillation frequencies and growth rates of modes in the MILO.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1989
- Accession Number
- ADA207793
Entities
People
- Raymond W. Lemke
Organizations
- Air Force Research Laboratory