Plasma diagnostics of non-equilibrium atmospheric plasma jets

Summary form only given. Intensive development and biomedical application of non-equilibrium atmospheric plasma jet (NEAPJ) facilitates rapid growth of the plasma medicine field. Non-equilibrium atmospheric plasmas are utilized for sterilization, disinfection, cancer treatment, drug delivery, dermatology, wound healing, etc. The NEAPJ facility utilized at the George Washington University (GWU) demonstrated efficacy for treatment of various cancer types (lung, bladder, breast, head, neck, brain and skin). In this work we review recent advances of the research conducted at GWU concerned with the development of diagnostic tools for NEAPJ. GWU experimental facility utilizes NEAPJ powered by about 20-30 kHz AC high-voltage source (up to 4-5 kV). The NEAPJ uses central electrode with non-insulated metal tip on the axis of the discharge tube (4 mm outlet diameter) and grounded ring electrode. The device operates with helium (typically around 11-12 L/min) and produces 4-5 cm length jet. Diagnostic tools include Rayleigh Microwave Scattering facility, DC potential scattering setup, Rogowski coils, ICCD camera and optical emission spectroscopy. These tools allow conducting temporally-resolved measurements of plasma density, electrical potential, charge and size of the streamer head, electrical currents flowing though the jet, ionization front propagation speed etc. Transient dynamics of plasma and discharge parameters will be considered and physical processes involved in the discharge will be analyzed including streamer breakdown, electrical coupling of the streamer tip with discharge electrodes, factors determining NEAPJ length, crosssectional shape and propagation path etc.