Characterization of a novel microwave plasma sheet source operated at atmospheric pressure

Abstract

Typically, microwave plasma sources (MPSs) operated at atmospheric pressure deliver plasmas in the common form of flames or cylindrical columns. In contrast to that, in this paper, a novel MPS (recently patented by us) for generating a new type of plasma in the form of a plasma sheet, which is sustained within a dielectric flat cuboid box, is presented. It is waveguide based, operated at a frequency of 2.45 GHz and in argon at atmospheric pressure. The plasma sheet consists of many filaments, typical of a microwave argon plasma. The MPS is described and analyzed in terms of optical emission spectroscopy, simulation of the electric field distributions in the MPS and numerical modeling of the working gas flow. Depending on the argon flow rate and absorbed microwave power, the determined electron density and rotational temperatures of OH radicals ranged from 3.6×10 14 to 5.6×10 14 cm −3 and from 800-1250 K, respectively. Numerical simulations have confirmed that the dimensions of the box are chosen correctly to ensure a sufficiently homogeneous distribution of the gas flow velocity field. The calculated electromagnetic field distributions in the MPS with plasma have shown that the device is well matched to the feeding line. The relative simplicity of the presented plasma source and industrially convenient plasma shape make it attractive for practical applications in the surface treatment of various materials.

Surface Modification of Polycarbonate by an Atmospheric Pressure Argon Microwave Plasma Sheet

“…In these conditions, the plasma sheet outside the box was about 50 mm in width, 10 mm in length, and 1 mm thick. As it was presented in Reference [25], for the microwave absorbed power of 850 W and the argon flow rate of 20 L/min, the temperature of OH radicals (assumed to be close to the gas temperature) determined using optical emission spectroscopy was about 1100 K. It was also found out that the rotational temperature of OH radicals increases with the increase of the absorbed microwave power and decreases with increasing the argon flow rate [25,44]. The treated polycarbonate samples were placed on a motorised (with stepper motor) linear stage.…”

“…A novel microwave (2.45 GHz) plasma source (MPS) using atmospheric pressure argon [44,45,46] was used for the surface modification of polycarbonate materials. In contrast to the other MPSs operating at atmospheric pressure, which deliver plasmas in the form of cylindrical plasma columns sustained inside a dielectric tube [53,54] or flames protruding outside of the dielectric tube [55,56], or a flame generated at the tip of a nozzle [57,58], the MPS used in the presented paper generates a very conveniently shaped plasma sheet.…”

“…This simple, low cost, and easy to operate novel microwave plasma source can be scaled up relatively easily to an industrial production line for material surface modification. The characteristics of the novel microwave plasma source and properties of the plasma sheet in terms of visualisation of the plasma sheet, optical emission spectroscopy, simulation of the electric field distributions, and numerical modelling of the plasma-forming gas flow are presented in References [44,45,46].…”

Impact of Atmospheric Pressure Microwave Plasma Treatment on Quality of Selected Spices

“…The argon flow rate was set at 20 L/min. Under these conditions, the plasma sheet outside the box was about 50 mm width, 10mm length and 1 mm thick, and the temperature of the plasma was about 900-950 K [25]. The treated spices were placed on a Petri dish on the motorized (with stepper motor) linear stage.…”

“…Applications of atmospheric pressure microwave plasma are very wide. Such plasmas can be used for gas processing [20,21], surface modification [22] or for biomedical decontamination [14,[23][24][25]. Because of the specific determinants of microwave generated plasma, especially the fact that it can operate under atmospheric pressure, it can be used in the food industry.…”