Current transformer as power sensor for cold atmospheric plasmas

This technology allows to measure plasma voltage and plasma current simultaneously and with a combined device in the high-voltage circuit of a cold atmospheric plasma. From this, the discharge power of the plasma can subsequently be calculated. The new measuring device is compact and a cost-effective alternative to the measuring technology normally required. Due to the good time resolution and the almost simultaneous measurement of the electrical parameters in the high-voltage branch, real-time measurements are possible, so that a plasma could regulate itself live with the help of the obtained measured values.


The simultaneous measurement of plasma voltage and current in pulsed, cold atmospheric pressure plasmas is complex and often associated with errors. Furthermore, relatively expensive equipment consisting of oscilloscope, high voltage probe and clampable current probe is currently required. Due to their complexity, the combination of these measuring devices harbors further sources of error, especially since it is not possible to measure current and voltage on the high-voltage side of the plasma simultaneously due to the relatively poor time resolution. Currently, for commercial applications, the generated plasma is appropriately characterized and sized and adjusted for the particular application prior to use. Manufacturers of plasma devices are currently reluctant to vary or control the plasma power during operation because they cannot measure electrical parameters live and accurately enough.

Our solution

For cold atmospheric pressure plasmas, a Current Transform (CT) sensor was developed at HAWK that simultaneously measures current and voltage in the high voltage circuit. In doing so, the sensor functions as a "clamp-on" solution by being clamped around a cable, allowing it to non-invasively determine currents and voltages flowing through the cable. This approach also simplifies installation. The sensor is compact, cost-effective and capable of measuring current and voltage simultaneously or with very short resolution times on the high-voltage side. The secondary-side measurement is more challenging, but also much more precise than the measurement on the primary side of the plasma. Therefore, some electrical effects can even be observed only on the high voltage side and after the transformer. In addition, power losses from the transformer are not measured as well. By using it to measure the discharge power of a plasma, cost-intensive components such as the usally used high-voltage probe, clampable current probe and oscilloscope for the measurement can be replaced and thus saved. Furthermore, the device stands out from competing methods due to its compactness and the combination of several previously required devices in one system. As a result, the system has a faster resolution time, is less complex, reliable and therefore less prone to error, and is less expensive than the competition of multiple individual devices used to date. In addition, the time resolution is adjustable due to the discrete electronic elements used and can therefore be planned in advance. In this way, custom-built CTs could be designed for particularly challenging applications at relatively low cost.

MM-2387-HAWK-imageCurrent Transformer with simplified electrical schematic (source: Hochschule für angewandte Wissenschaft und Kunst – Hildesheim/Holzminden/Göttingen)


  • Non-invasive clamp-on sensor for easy installation
  • Compact, cost-effective and capable of measuring current and voltage simultaneously on high-voltage side of the cold atmospheric plasma
  • Saves user money compared to the usually needed setup (high-voltage probe, clampable current probe and oscilloscope)
  • Combination of these mentioned devices into one system
  • Faster time resolution which can be easily tuned to the corresponding electronic demands


  • Current transformer as power sensor for cold atmospheric plasmas to measure plasma voltage and current simultaneously
  • Self-regulating plasma due to simultaneous measurement of the electrical parameters

Development status

Current transformer built up in the lab, proof of concept shown

Patent status

Hochschule für angewandte Wissenschaft und Kunst – Hildesheim/Holzminden/Göttingen
EP22187261.7 (filed)




Dr. Markus Muchow
Patentmanager Physik, Technik und Software
E-Mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Tel.: +49 551 30724 159
Reference: MM-2387-HAWK

Tags: Plasma physics, Physics and Technology & Software


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