Electrodeless Atmospheric Secondary Induced Ionization plasma jet – EASII-jet

Non-equilibrium atmospheric pressure plasma jet (APPJ) devices are promising plasma sources for many kinds of applications. APPJs have already demonstrated their unique potential to trigger biological responses valuable in medicine and biology. It has also been involved in various application such as water and liquid activation, agriculture, surface modifications and active flow control. Operating in ambient air, APPJs can be easy to design and to implement in to already existing industrial systems. Their high potential to produce localized highly reactive oxygen and nitrogen species (RONS) is of significant interest in many fields of applications. Usually made of a –transparent– dielectric tube of a few centimeters long, it is equipped with a pair of electrodes connected to a HV power supply. Noble gas (typically helium or argon) flows into it at flow rate in the order of a liter per minute. The latter having a lower ionization energy threshold than air, ionization waves (IW) are produced in the vicinity of the power electrode. The IW propagates within the He flowing into the tube before to expand outside guided by the He plume and forming a luminous plasma plume of a couple of cm long.

Taking advantage of the intriguing feature of IWs to be transferred across a dielectric layer up to a few mm, electrodeless guided IWs can be produced and totally isolated from the power supply. In this contribution, an original type of APPJ will be introduced. The dynamic of the secondary induced ionization waves is investigated experimentally using filtered iCCD imaging techniques, high-resolution optical emission spectroscopy and electrical measurements. Three operating modes have been identified depending on the HV excitation properties (voltage amplitude and pulse width). By changing from one mode propagation to another with respect to the pulse width duration, the elementary mechanisms will be discussed.