Improving Performance of Crossed-Field Amplifiers Through Modulation Injection
Abstract
Microwave vacuum electron devices (MVEDs) are critical for military infrastructure from radar and communications to electronic warfare, including emerging directed energy applications. While MVEDs are dominant in high frequency and high power regimes, improved device performance is essential to maintain the advantage over solid state devices. In particular, crossedfield devices, such as crossed-field amplifiers (CFAs), offer high efficiency, high power density, and robust performance. Improved CFA gain-bandwidth product and reduced noise would contribute to greater use and operational capabilities. Currently, there are no high power CFA models available for public research studies at universities. This gap is especially important as we try to realize the promise of higher power devices represented by directed energy high-power radiofrequency (HPRF) devices. Almost every type of HPRF device is an oscillator. While thesesources produce very high power pulses, the waveform control, typically measured in the bandwidth, is insufficient for radar or communications. This restricts these directed energy (DE) sources to jamming and counter-electronics missions, rather than the more information-intense full-fledged electronic warfare. This proposal goes to the heart of the question what are the limitsto high-power amplifiers?This proposed effort will study the effects of electron modulation on a high power (1 MW) L-Band CFA using theory (Purdue University) and simulation using the particle-in-cell codes ICEPIC (Confluent Sciences) and V-Sim (Boise State University and Tech-X). The first task entails developing and validating a CFA model using thermionic emission models. This result will next be combined with secondary emission models and theories and validated. This will subsequently permit the examination of the causes of drive saturation and gain-bandwidth limitations. This combined theory and simulation will then be used to characterize the effects of electron modulation with and without secondary emission on gain, bandwidth, saturation, and noise on CFA efficiency, pulse width, output power, bandwidth, and frequency timing. Finally, an assessment on the impact of noise in the CFA will be performed by examining how particle orbits are impacted based on the thermionic and secondary emission models and the impact of spacecharge on the electromagnetic properties of the device. This will involve including sensitivity analysis into the theoretical studies of single electron orbits, including second emitter into the theory and studying the interaction between electrons emitted from each source, and using simulation to examine electromagnetic mechanism in more detail. The electromagnetic spectrum is becoming both congested and contested, requiring greater flexibility in electromagnetic sources. As platforms become much more loaded with electronics and technology, the compactness, efficiency, capability, and controllability of individual electromagnetic sources must increase. Therefore, this proposal strives to both maintain the high amplitude operation associated with DE technology and determine ways in which DE devices can provide information rich signals with choices in center band frequency, high bandwidth frequency modulation, and exquisite phase control. Traditional crossed-field DE devices, such as magnetrons, operate at high amplitude, but with only modest bandwidth or shot-to-shot frequency control. Incontract, the CFA provides bandwidth and phase control, but with orders-of-magnitude lower power. Thus, the CFA characterization proposed here wiy, which is critical for electromagnetic warfare.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 06, 2021
- Source ID
- N000142112024
Entities
People
- Allen L Garner
Organizations
- Office of Naval Research
- Purdue University
- United States Navy