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Stub tuners are used in microwave design to match load impedances to allow for maximum power transfer between generator and load.  They consist of one or more transmission lines that have tunable lengths and are each terminated with an open or short-circuited load.  Despite their importance, appropriate mechanisms for stub tuning are limited.  There is a need for a tunable mechanism that could withstand high electric fields to enable high-power microwave (HPM) sources.


Design and construction of a photoconductive switch requires a diamond photoconductor illuminated by light of a certain excitation wavelength.  The diamond material is specifically doped with substitutional nitrogen, which act as a source of electrons.  The device architecture allows maximum light entering the aperture.  The top and bottom electrodes are made of ultra wide band gap (UWBG) transparent conductors or materials with high reflectivity.

  • Able to withstand extremely high electric fields
  • Fast turn-on times
  • Tunable to desired properties of the mission
  • Applicable to high power electronics, pulsed power, and particle accelerator applications
Potential Applications
  • Directed energy and effects testing
  • Electronic warfare
  • Long-range communication and radar
  • Industrial microwave heating or curing
  • Pulsed power and particle accelerators
Development Status

Current stage of technology development:  TRL 2 (Technology concept and/or application formulated)

LLNL has filed for patent protection on this invention.

Reference Number