Abnormal glow discharges in Ar: experiments and models

Phelps, A. V.

doi:10.1088/0963-0252/10/2/323

Cited by 79 publications

(69 citation statements)

References 116 publications

(351 reference statements)

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“…At a high pressure, i.e., 10 Torr, on the other hand, the I-V characteristics show positive resistance. We note that, at lower pressures, the I-V characteristics is also different from the well-known I-V characteristics Jn -2 (here, J is the current density and n is the neutral particle density) scaling in the absence of a magnetic field [11].…”

Section: Current-voltage Characteristicscontrasting

confidence: 73%

“…3. The breakdown voltage curves with a magnetic field show more interesting features at lower pressures (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) Torr in the case of He discharges). When the electrode with the magnetic circuit is powered at negative voltages, the breakdown voltages are found to be significantly lower than those for discharges without magnetic field.…”

Section: Breakdown Voltage Measurementsmentioning

confidence: 99%

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Magnetized microdischarge plasmas in low pressure argon and helium

Kobayashi

Ito

Cappelli

et al. 2008

J. Phys.: Conf. Ser.

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Magnetized microdischarge plasmas in low pressure argon and helium Abstract. Magnetized microdischarge plasmas have been generated in low pressure argon and helium environments with planar electrodes and a non-uniform magnetic field configuration that can cause closed E×B electron drift. The electrode gap was 1 or 3 mm and the operating gas pressures were 0.5-55 Torr for argon or 1-100 Torr for helium. The breakdown voltage is found to be low with the use of a magnetic field at lower pressures as a result of the effective magnetization of electrons. The current-voltage relation at low pressures departs from the well-known current-voltage scaling that holds in the absence of a magnetic field. The magnetized microdischarge system for argon with copper electrodes exhibits a transition from positive to negative resistance when the operating pressure is decreased to below 10 Torr. IntroductionThe development of microdischarges, microplasmas, or micro-ion sources has attracted much interest for a range of applications, such as local etch processing [1], chemical analysis [2], materials synthesis [3,4], surface treatment/modification [5], and sterilization [6]. It has been demonstrated that microdischarges can be ignited and sustained at relatively high pressures, removing the necessity of vacuum chambers in some cases. However, as a trade-off of this, the operation in a highly collisional environment precludes applications that may require high ion energy. At low pressures and low powers, the generation and operation of a microdischarge may develop new fields of applications that benefit from focused, high current density, and highly energetic ions, such as spatially constrained surface treatment or modification, sputtering, low energy ion implantation, and micropropulsion. By using a magnetic field, we have demonstrated microdischarge generation under low pressure environments [7,8] and its application to the development of a micropropulsion device [9].In this paper, we present a basic characterization of a direct-current (DC) magnetized microdischarge plasma, which is generated with planar electrodes and a non-uniform magnetic field configuration promoting closed E×B electron drift in argon and helium environments. Furthermore,

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Section: Current-voltage Characteristicscontrasting

confidence: 73%

Section: Breakdown Voltage Measurementsmentioning

confidence: 99%

Magnetized microdischarge plasmas in low pressure argon and helium

Kobayashi

Ito

Cappelli

et al. 2008

J. Phys.: Conf. Ser.

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“…by the long path breakdown [15]. The second scaling that has been tested is j/p 2 , which is connected to the effect of space charge [17]. It was shown that for standard size discharges both pd (and E/N) and j/p 2 scalings are valid in parameter region around Paschen minimum [11].…”

Section: Properties Of Micrometer Size Discharges -Scaling Lawsmentioning

confidence: 99%

“…Our knowledge on basic processes in standard size discharges provided us with a possibility to investigate basic properties of micro-discharges from the point of view of scaling laws [16,17]. This type of nonequilibrium discharges with rising number of applications is inaccessible for most standard diagnostic tools due to its small size.…”

Section: Introductionmentioning

confidence: 99%

Breakdown and discharge regimes in standard and micrometer size dc discharges

Škoro¹

2012

J. Phys.: Conf. Ser.

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Breakdown and discharge regimes in standard and micrometer size dc discharges Abstract. In this paper, an overview of our recent experimental studies of the breakdown and operation of non-equilibrium discharges in centimetre and micrometer size geometries is presented. In the centimetre size geometries, we focused on elementary processes and phenomenology in gases used for some of the currently most attractive applications of low temperature plasmas -fluorocarbon gases (CF 4 , CHClF 2 ) and water vapour. Measurements were performed at electrode separation d = 1.1 cm, in a pressure range from 0.1 to 5 Torr. In the case of micro-discharges, the emphasis was on testing the validity of standard scaling laws and proper determination of scaling parameters pd and j/p 2 . This was done at electrode gaps of 200 and 500 μm and pressures of 50 and 20 Torr in argon. The investigation is based on measurements of breakdown potentials (Paschen curves) and Volt-Ampere characteristics, supported by simultaneous ICCD imaging of the discharges. IntroductionOwing to many unique properties, low temperature non-equilibrium discharges have been used in a large number of applications. Fundamental investigations lead to new applications but, recently, in many cases, the needs of applications led to numerous fundamental results. On all accounts, the complexity of these discharges call for full understanding of discharge processes in order to make efficient and reliable devices. Moreover, along with numerous non-equilibrium discharge sources in centimetre size [1,2], many sources with micrometre characteristic dimensions have been introduced recently [3,4]. Hence, an ongoing direction of research about discharges in molecular gases and gas mixtures of interest for applications [5] has been appended with new challenges of discharges taking place between electrodes separated by few tens or hundreds of micrometers -micro-discharges [6]. Additionally, a new type of non-equilibrium discharges taking place in or near liquids has emerged [7], bringing new possibilities for applications together with a whole new set of issues to resolve.Accordingly, results presented in this paper are divided in two sections. The first one deals with measurements conducted with cm-size chamber. Using previously gathered experience on standard size non-equilibrium discharges in rare gases at low pressures [8][9][10][11][12], our research is continued with experimental measurements in gases of interest for applications: fluorocarbons (CF 4 and CHClF 2 ) which are widely used for plasma etching (e.g. [13]) and water vapour that is present as working environment of numerous commercial devices [14]. Measurements in these gases aim to provide reliable and systematic data sets required for plasma models that may be extended to applications involving those gases.

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“…This is in principle identical to electron-hybrid models used in lowpressure glow discharges. 13 Its development is built on our previous work 12 and is similar to that used recently for radiofrequency APGD. 11 It is worth mentioning that the hybrid approach has achieved quantitative agreement with most available experimental data for DC APGD ͑Ref.…”

Section: Introductionmentioning

confidence: 99%

Electron kinetic effects in atmospheric dielectric-barrier glow discharges

Zhu

Kong

2005

Journal of Applied Physics

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Large-volume atmospheric dielectric-barrier discharges (DBD) are particularly useful for processing applications when they operate in their homogeneous mode. A vast majority of their theoretical studies is currently based on the hydrodynamic treatment in which electrons are assumed to be in equilibrium with the local electric field. Recognizing that this assumption is incorrect in the sheath region, we report the development of an electron-hybrid model to treat electrons kinetically and all other particles hydrodynamically. Through numerical examples, it is shown that the mainstream hydrodynamic model underestimates gas ionization and discharge current. Using the hybrid model, it is demonstrated that variation in the amplitude of the applied voltage does not significantly alter sheath characteristics in terms of the electric field and the electron mean energy. Also gas ionization in atmospheric DBD is found to be significant only over a short timescale of 1 μs. Compared with dc atmospheric pressure glow discharges, atmospheric DBD are shown to have a smaller electron mean energy and a larger sheath thickness.

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Abnormal glow discharges in Ar: experiments and models

Cited by 79 publications

References 116 publications

Magnetized microdischarge plasmas in low pressure argon and helium

Magnetized microdischarge plasmas in low pressure argon and helium

Breakdown and discharge regimes in standard and micrometer size dc discharges

Electron kinetic effects in atmospheric dielectric-barrier glow discharges

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