High-Efficiency Microwave Plasma Jet


­Project ID: D2021-25


Plasma jets are currently made with bulky and expensive equipment that consumes a lot of energy. Most commercially available plasma jets utilize high-voltage pulses (e.g., 100s of V to kV) or high-power radio frequency (RF) sources (e.g., 10s of W), even though low-power plasma with effective surface power density in the order of 0.1 to 1 W/cm2 is sufficient for many applications. High-power sources also create safety concerns. Therefore, there is a need for a low-power, efficient, and safe plasma jet that could enable the technology to be used in a wider variety of applications.


Invention Description

Utilizing microwaves, the plasma jet forms in an evanescent-mode (EVA) cavity resonator that concentrates the electromagnetic energy over a small volume to create a significantly efficient plasma jet. Due to the high quality factor of the EVA cavity resonator, it is possible to have a stable plasma jet even by an input power in the range of milliwatts. The frequency of operation can be tuned, and the plasma jet size and density can be controlled by both the gas flow rate and the input microwave power.


  • Plasma medicine
  • Food/water/agricultural decontamination
  • Reconfigurable RF electronics
  • Material processing
  • Flow control
  • Electric propulsion/combustion


  • Higher efficiency compared to RF or pulse excitation (> 80%)
  • Can be fabricated at a lower cost (e.g., if implemented by SIW PCB technology)
  • Can operate with different gas types (e.g., Helium, Argon, and Neon)
  • Tunable frequency and plasma size/density
  • Lower energy consumption
  • Compact device
  • Safer for biomedical applications

IP Status:                   Patent Pending

Patent Information:
For Information, Contact:
Katherine Pollard
Licensing Associate
The University of Toledo
Abbas Semnani
Plasma jet