In a two-cavity klystron amplifier, what is the correct order of major parts from the electron source onward?

Introduction:
Two-cavity klystron amplifiers use velocity modulation and bunching to convert DC beam power into RF output. Knowing the structural order is essential to understand energy transfer and gain mechanisms.

Given Data / Assumptions:

• Device: two-cavity klystron amplifier
• Key regions: electron gun (cathode), buncher cavity, drift space, catcher cavity, collector/anode

Concept / Approach:
Electrons emitted by the cathode are velocity-modulated in the buncher cavity. During the drift space, faster electrons catch slower ones to form bunches. These bunches induce strong RF currents in the catcher (output) cavity, transferring kinetic energy to RF. Finally, spent electrons are collected at the collector/anode.

Step-by-Step Solution:

Verification / Alternative check:
Standard block diagrams in microwave textbooks follow this exact sequence.

Why Other Options Are Wrong:

• A/C/D: Misordered elements; for example, placing anode or catcher before buncher contradicts the velocity-modulation-first principle.

Common Pitfalls:
Confusing reflex klystron (with repeller) with multi-cavity amplifier; omitting the drift space where bunching develops.

Final Answer:
Cathode (electron gun), buncher cavity, drift space, catcher cavity (output), collector/anode