Subterahertz Photonic Crystal Klystron Amplifier

Area of Science:

• Physics
• Electrical Engineering
• Materials Science

Background:

• Klystrons are vacuum electronic devices crucial for generating high-frequency electromagnetic waves.
• Extending klystron operation into the subterahertz and terahertz (THz) regions presents significant technological challenges.
• Photonic crystals offer unique electromagnetic wave manipulation properties that can be leveraged in device design.

Purpose of the Study:

• To experimentally demonstrate the amplification of subterahertz radiation in a klystron utilizing photonic crystal cavities.
• To investigate the performance characteristics of a novel klystron design incorporating oversized photonic crystal cells.
• To validate simulation predictions with experimental results for a photonic crystal klystron amplifier.

Main Methods:

• Fabrication of a six-cavity klystron with oversized photonic crystal cells featuring a central beam tunnel.
• Operation of a pulsed electron beam (23.5 kV, 330 mA) within a 0.5 T solenoidal magnetic field.
• Measurement of small-signal gain and saturated output power at 93.7 GHz.

Main Results:

• Achieved a small-signal gain of 26 dB at 93.7 GHz.
• Obtained a saturated output power of 30 W.
• Experimental results showed excellent agreement with particle-in-cell code simulations.

Conclusions:

• Successfully demonstrated high gain amplification of subterahertz radiation using a photonic crystal klystron.
• The novel design with oversized photonic crystal cavities enables efficient power coupling and high-frequency operation.
• This work represents a significant step towards realizing klystron amplifiers in the terahertz frequency range.