PHASE LOCKED HIGH POWER MICROWAVE SOURCES
Abstract
For a given accelerating voltage, HPM sources are restricted in peak power. While increasing the accelerating voltage can increase the power, this has an adverse impact on HPM source size, complexity and reliability. An alternative approach is to combine multiple sources coherently. Division of the driving voltage pulse across several parallel channels equipped with independent electron guns provides the potential for several (N) high power sources to be controllably phased in a two-dimensional array to produce intensity equivalent to N2 power from a single HPM source. Beam steering is also possible. High Power Oscillators based on Cherenkov radiation from relativistic electron beams moving in a slow wave structure (SWS) can be synchronised if the edge of the current pulse is sufficiently fast compared to the signal frequency. Spontaneous emission of the bunch edge serves as the seed for stimulated processes that include electron self-bunching and subsequent generation of high-power electromagnetic (EM) radiation. When synchronised current pulses are sent to several oscillators, in-phase microwave pulses can be generated, enabling coherent summation of their amplitudes. If a precise time shift in the beam current rising edge can be produced, precise control of the phase of the oscillator can be achieved. In X-band the period of oscillation is of the order of 100ps. To ensure synchronisation of the BWO sources, delays in the range -50ps to +50ps are therefore required. Delay accuracy of the order of 10ps is desirable. Controllable delays in this range can be produced using a saturable ferrite placed in the transmission lines between generator and the cathode of the electron gun.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 11, 2021
- Source ID
- FA86552017011
Entities
People
- Adrian Cross
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Strathclyde