In a backward-wave oscillator (BWO), does the guided RF wave physically 'wind back and forth' along the line?

Introduction / Context:
A backward-wave oscillator (BWO) is a vacuum device where the phase velocity of the slow-wave structure supports a wave whose phase travels opposite to the direction of power flow. This enables oscillation under proper feedback conditions.

Given Data / Assumptions:

• BWO with slow-wave structure (e.g., a helix or periodic waveguide).
• Electron beam interacts with a backward wave (negative phase velocity relative to the beam).

Concept / Approach:

'Backward wave' refers to the direction of phase propagation relative to energy flow, not a literal 'winding back and forth' of energy or the field structure along the line. The energy still travels toward the output; it is the phase that appears to move backwards. Therefore, the statement that the wave 'winds back and forth' is inaccurate and misleading.

Step-by-Step Solution:

Verification / Alternative check:

Device analyses show negative dispersion slope (backward wave) with unidirectional energy transport; measured output confirms delivered power at the output port without 'shuttling' back and forth.

Why Other Options Are Wrong:

• True (and qualifiers): Misinterpret the meaning of backward-wave as a physical zig-zag of energy.
• Depends on beam voltage: Beam voltage affects frequency and gain, not the fundamental definition of backward wave.

Common Pitfalls:

Equating negative phase velocity with negative energy flow; misreading cartoons of slow-wave structures as literal field paths.

Final Answer:

False