Low-Intrusion Plasma Probe

Tech ID: 30476 / UC Case 2019-023-0


UCLA researchers in the Department of Mechanical and Aerospace Engineering have developed an inexpensive and easily implemented plasma diagnostic tool, the Low-Intrusion Probe.


Plasma diagnostic tools, which measure the properties of plasmas, are widely used in analytical techniques for defense, electric propulsion, nuclear fusion research, material processing, and medicine. For example, plasma diagnostics are used for in situ studies of nanostructures formation during the synthesis processes. The most common method of diagnosing a plasma is a Langmuir probe, which are simple to construct, implement, and analyze. However, Langmuir probes inherently change the properties of the plasma under study. Additionally, the operation of the device requires drawing current from the plasma. This intrusive nature alters the plasma enough to introduce significant uncertainties in the data and can potentially disrupt processes that may be critical to the nominal operation of the device. Non-intrusive plasma diagnostics, such as interferometry, can limit plasma perturbations during measurements, but at higher laser light power levels, the technique can change the local plasma properties. Moreover, interferometry is very complicated and costly to implement.


UCLA researchers have developed a novel plasma diagnostic tool, the Low-Intrusion Probe. This probe couples electromagnetic fields into a plasma using a metamaterial, and uses a simple analysis technique to extract the plasma properties. Current collection is not required to diagnose the plasma, thereby mitigating disruptions to the plasma during measurement. The Low-Intrusion Probe offers an inexpensive and easily implemented method of determining electron density that can be used as a standalone diagnostic, or as a complement to a plasma diagnostic suite, such as Langmuir Probes, to reduce the overall measurement uncertainty. Moreover, it expands the number of regimes and locations in which a plasma can be characterized in most mainstream applications. This diagnostic tool offers a middle ground between the inexpensive-yet-intrusive Langmuir probe, and the expensive-yet-non-intrusive interferometry technique.


  • Nuclear fusion research
  • Spectroscopy
  • THz spectroscopy
  • Research tools (In-situ studies)
  • Electric Propulsion
  • Plasma etching
  • 3D printing


  • Current collection not required to diagnose plasma
  • Minimizes plasma perturbation during measurement
  • Inexpensive and easily implemented
  • Can be used in-tandem with Langmuir Probes to reduce overall measurement uncertainty

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Patent Status

Patent Pending


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  • Wirz, Richard E.

Other Information


Plasma diagnostics, Low-Intrusion Probe, Langmuir Probe, plasma properties, metamaterial, interferometry, nuclear fusion research, microstrip, in situ studies, THz spectroscopy

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