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Traveling-wave tubes and backward-wave oscillators with weak external magnetic fields
T M Abu-elfadl1, G S Nusinovich, A G Shkvarunets
1Institute for Plasma Research, University of Maryland at College Park, College Park, Maryland 20742-3511, USA.
Summary
Weak magnetic fields enhance plasma-assisted slow-wave oscillators by improving electron coupling and efficiency. This allows for shorter interaction regions and prevents electron interception by the slow-wave structure (SWS).
Area of Science:
- Plasma Physics
- Microwave Engineering
- Electron Beam Devices
Background:
- Plasma-assisted slow-wave oscillators (SWOs) are magnetic field-free microwave sources.
- Radial electron motion in SWOs can enhance electron coupling to slow waves, increasing efficiency.
- Uncontrolled radial motion can lead to electron interception by the slow-wave structure (SWS).
Purpose of the Study:
- To theoretically analyze the effect of weak magnetic fields on SWOs.
- To determine the magnetic field required to prevent electron interception by the SWS.
- To investigate efficiency enhancement in traveling-wave tubes and backward-wave oscillators.
Main Methods:
- Developed a theoretical model for electron motion in SWOs with weak magnetic fields.
- Included axial and transverse electron movement in the theoretical analysis.
- Estimated magnetic field requirements for different power levels to protect the SWS.
Main Results:
- Weak magnetic fields can beneficially guide electrons, preventing interception by the SWS.
- Theoretical predictions show efficiency enhancement due to weak magnetic fields.
- Experimental results confirm the theoretical predictions of efficiency enhancement.
Conclusions:
- Weak magnetic fields are crucial for optimizing plasma-assisted SWOs operation.
- The developed theory accurately predicts the magnetic field needed for SWS protection.
- Applied magnetic fields enhance efficiency and allow for shorter interaction regions in SWOs.