Dielectric-barrier discharges (silent discharges) are used on a large industrial scale. They combine the advantages of non-equilibrium plasma properties with the ease of atmospheric-pressure operation. A prominent feature is the simple scalability from small laboratory reactors to large industrial installations with megawatt input powers. Efficient and cost-effective all-solid-state power supplies are available. The preferred frequency range lies between 1 kHz and 10 MHz, the preferred pressure range between 10 kPa and 500 kPa. Industrial applications include ozone generation, pollution control, surface treatment, high power CO2 lasers, ultraviolet excimer lamps, excimer based mercury-free fluorescent lamps, and flat large-area plasma displays. Depending on the application and the operating conditions the discharge can have pronounced filamentary structure or fairly diffuse appearance. History, discharge physics, and plasma chemistry of dielectric-barrier discharges and their applications are discussed in detail.

https://www3.nd.edu/~sst/teaching/AME60637/reading/2003_PCPP_Kogelschatz_dbd_review.pdf

Dielectric-barrier Discharges: Their History, Discharge Physics, and Industrial Applications

Cold Atmospheric Plasma is an ionized gas that has recently been extensively studied by researchers as a possible therapy in dentistry and oncology. Several different gases can be used to produce Cold Atmospheric Plasma such as Helium, Argon, Nitrogen, Heliox, and air. There are many methods of production by which cold atmospheric plasma is created. Each unique method can be used in different biomedical areas. In dentistry, researchers have mostly investigated the antimicrobial effects produced by plasma as a means to remove dental biofilms and eradicate oral pathogens. It has been shown that reactive oxidative species, charged particles, and UV photons play the main role. Cold Atmospheric Plasma has also found a minor, but important role in tooth whitening and composite restoration. Furthermore, it has been demonstrated that Cold Atmospheric Plasma induces apoptosis, necrosis, cell detachment, and senescence by disrupting the S phase of cell replication in tumor cells. This unique finding opens up its potential therapy in oncology.

/pdf/cold-atmospheric-plasma-methods-of-production-and-52fe5iy98m.pdf

Cold Atmospheric Plasma: methods of production and application in dentistry and oncology

The properties of ultraviolet (UV) and vacuum ultraviolet (VUV) radiation produced by excimer and exciplex molecules are presented The use of excimer and exciplex molecules in various discharges offers several merits Therefore, effective and bright UV and VUV sources can be created The characteristics of several typical excilamps (excimer and exciplex lamps) are described The extraordinary characteristics of excilamps led to a lot of applications, which had been demonstrated in a number of recent studies This review is dedicated to advances in application of UV/VUV electrodeless capacitive and barrier discharge excilamps in photoscience (ie in photochemistry, photobiology and photomedicine), namely, applications for oxidation and mineralization of organic substrates; VUV-initiated photodimerization and removal of water from hydrocarbon gas mixtures; UV inactivation of biological systems; UVB phototherapy of skin diseases; applications for inorganic analyses of environmental samples and for UVB/UVC photoregulation of plants Further, tendencies in the development of excilamps and accompanying technologies are presented

Applications of capacitive and barrier discharge excilamps in photoscience

Living mammalian cells and bacteria were exposed to irradiation from narrow-band UV lamps and treated with a nonthermal gas plasma (plasma needle). The model systems were: Chinese Hamster Ovary (CHO-K1) cells (fibroblasts) and Escherichia Coli bacteria. UV irradiation can lead to cell death (necrosis) in fibroblasts, but the doses that cause such damage are much higher than those needed to destroy Escherichia Coli. The usage of UV radiation in combination with active oxygen radicals lowers the UV dose sufficient to kill the cells. However, in any case the fibroblasts seem to be fairly resistant to UV radiation and/or radicals. Possibly, the lamps may be used for decontamination of infected wounds. The most important active species in an atmospheric plasma are the radicals; the role of UV is less pronounced. Treatment of CHO-K1 cells with the plasma needle can lead to cell necrosis under extreme conditions, but moderate doses cause only a temporary interruption of cell adhesion. Plasma needle may be used for fine tissue treatment (e.g., controlled cell removal without inflammation) and also for bacterial decontamination.

The effects of UV irradiation and gas plasma treatment on living mammalian cells and bacteria: a comparative approach

The results of research into high-power, high-efficiency noble-gas-halide excilamps using glow, capacitive, and barrier discharges for the excitation sources are presented. The maximum radiation powers and minimum consumption are achieved with glow discharge lamps. An excilamp with an average radiation power of 1.6 kW on KrCl* molecules (λ = 222 nm) and 1.1 kW on XeCl* molecules (λ = 308 nm) is developed, whose energy conversion efficiency exceeds 10%. The use of an electrodeless capacitive discharge leads to sealed off excilamps with a simple emitter design, which have a power of 1 to 10 W and a service life of about 2500 h and more. Barrier-discharge excilamps possess both high energy parameters (> 100 W m−1) and a long service life. Excilamps can find wide practical applications as new powerful sources of UV and VUV radiation.

http://iopscience.iop.org/article/10.1070/PU2003v046n02ABEH001308/pdf

Excilamps: efficient sources of spontaneous UV and VUV radiation

The results of studies, development works, and tests of barrier-and capacitive-discharge excilamps radiating in the UV and VUV spectrum regions are presented. The main information on the designs of radiators and generators is presented. The spectral, temporal, and energy characteristics of excilamps based on the emission of KrCl*, XeCl*, XeI*, XeBr*, KrBr*, Xe*2, Br*2, and Cl*2 molecules and the I* atomic line are described. It is shown that the created generators and sealed-off radiators have long service lives. Examples of specific applications of excilamps are presented.

Capacitive and barrier discharge excilamps and their applications (Review)

It is shown that a volume discharge is formed in a nonuniform electric field for the short leading edge of a voltage pulse and nanosecond pulse duration without any additional preionisation source in various gases at pressures higher than atmospheric (6 atm in helium and 3 atm in nitrogen). Lasing at atomic transitions in Xe is obtained in an Ar—Xe mixture under a pressure of 1.2 atm for an active length of 1.5 cm. A record-high specific power input (more than 0.8 GW cm-3 under a pressure 1 atm in air) is realised in the volume discharge stage. The volume discharge is formed due to preionisation of the discharge gap by fast electrons accelerated due to amplification of the electric field in the cathode region and in the gap. In a nonuniform electric field, volume discharge is realised under a quasistationary voltage from 10 to 180 kV across the gap, at a pulse repetition rate of up to 160 Hz and for various discharge gap geometries.

https://iopscience.iop.org/article/10.1070/QE2004v034n11ABEH002658/pdf

Pulsed volume discharge in a nonuniform electric field at a high pressure and the short leading edge of a voltage pulse

This article reports on experimental studies of subnanosecond electron beams formed in air under atmospheric pressure. An electron beam with an amplitude of ∼170 A with a duration at FWHM of ∼0.3 ns has been obtained. Based on beam temporal characteristics and discharge spatial characteristics, the critical fields were supposed to be reached at plasma approach to anode. Simultaneously, the sharp high-energy pulse of e-beam current is generated. Of critical importance is the cathode type and occurrence on the cathode of plasma protrusions. It is shown that to get maximum amplitude of the electron beam in the gas diode, the discharge in the gas diode should be volumetric.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0263034604221152

On formation of subnanosecond electron beams in air under atmospheric pressure

Lasing was observed in neon (λ = 585.3 nm) when dense (0.2–3 atm) Ne–H2 and Ne–Ar mixtures were pumped by an electron beam (40 A/cm3, 80 nsec). A population inversion appeared because the lower active level was cleared by the Penning reactions involving H2 and Ar.

V. S. Skakun

Papers

Excilamps: efficient sources of spontaneous UV and VUV radiation

Capacitive and barrier discharge excilamps and their applications (Review)

Pulsed volume discharge in a nonuniform electric field at a high pressure and the short leading edge of a voltage pulse

On formation of subnanosecond electron beams in air under atmospheric pressure

Plasma laser emitting at the wavelength of 585. 3 nm with Penning clearing of the lower level in dense mixtures with neon excited by an electron beam