Generation of ultrahigh frequency air microplasma in a magnetic loop and effects of pulse modulation on operation

Taghioskoui, Mazdak; Perlow, Joshua; Zaghloul, Mona; Montaser, Akbar

doi:10.1063/1.3429093

Cited by 11 publications

(3 citation statements)

References 13 publications

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“…Any reflected wave from the plasma discontinuity is primarily recycled by reflection from the grounded end of the microstrip line. A quarter-wave resonator is illustrated, but half-wave [21][22][23] and 3/4-wave resonators [24,25] behave in a similar fashion. A third microwave coupling strategy is sketched in figure 1(c).…”

Section: Microwave-driven Microplasma Topologiesmentioning

confidence: 99%

Microplasmas ignited and sustained by microwaves

Hopwood

Hoskinson

Gregório

2014

Plasma Sources Sci. Technol.

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The challenges and benefits of microwave-induced microdischarges are reviewed. Transmission lines, resonators and surface wave launchers may be used for coupling microwave power to very small plasmas. Fortunately, microplasmas are typically much smaller than the wavelength of microwaves, and the electromagnetic problem may be treated electrostatically within the plasma. It is possible to trap electrons within small discharge gaps if the amplitude of electron oscillation is smaller than the plasma size. Typically occurring above 0.3 GHz, this condition results in lower breakdown fields than are required by direct current or radio frequency systems. Trapping of electrons also decreases the electrode potential to only tens of volts and makes the plasma density invariant in time. The steady-state microplasma produces electron densities of up to 10 15 cm −3 in argon but the electrons are not in equilibrium with the low gas temperatures (500-1000 K). Microwave discharges are compared with other forms of microplasma and guidelines for device selection are recommended. Scale-up of microplasmas using array concepts are presented followed by some exciting new applications.

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Section: Microwave-driven Microplasma Topologiesmentioning

confidence: 99%

Microplasmas ignited and sustained by microwaves

Hopwood

Hoskinson

Gregório

2014

Plasma Sources Sci. Technol.

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“…Pulse modulation has been demonstrated to facilitate plasma ignition and to reduce the required ignition/operation power and in UHF plasmas. 34,41 In this work, pulse-modu-lation was used during initial plasma formation. However, after generating the plasma, pulse modulation was switched off and the plasma was supplied with an amplified UHF sinusoidal signal of 962 MHz, because mass spectral profile deformation was observed during preliminary mass spectrometric measurements when the pulse modulation was on.…”

Section: Icp Ignition and Operationmentioning

confidence: 99%

“…For example, plasma sources that operate in ambient air at atmospheric pressure do not require supplementing inert gases, such as helium or argon, and/or pumps for operation, resulting in simpler hardware. 34 Plasma formation under ambient Martian conditions translates into formation of a plasma with the native Martian atmospheric pressure and composition. The atmospheric pressure on Mars varies from around ∼0.2 Torr on the Olympus Mons peak to over ∼8.7 Torr in the depths of Hellas Planitia, with a mean surface level pressure of ∼4.5 Torr.…”

Section: Introductionmentioning

confidence: 99%

Plasma ionization under simulated ambient Mars conditions for quantification of methane by mass spectrometry

Taghioskoui

Zaghloul

2016

Analyst

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Ambient ionization techniques enable ion production in the native sample environment for mass spectrometry, without a need for sample preparation or separation. These techniques provide superior advantages over conventional ionization methods and are well developed and investigated for various analytical applications. However, employing ambient ionization techniques for in situ extra-terrestrial chemical analysis requires these techniques to be designed and developed according to the ambient conditions of extra-terrestrial environments, which substantially differ from the ambient conditions of Earth. Here, we report a plasma ionization source produced under simulated ambient Mars conditions for mass spectrometry. The plasma ionization source was coupled to a quadrupole mass spectrometer, and quantitative and qualitative analyses of trace amounts of methane, as an analyte of interest in Mars discovery missions, were demonstrated. The miniature plasma source was operational at a net power as low as ∼1.7 W in the pressure range of 4-16 Torr. A detection limit as low as ∼0.15 ppm (v/v) at 16 Torr for methane was demonstrated.

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Microwave Plasma Systems in Optical and Mass Spectroscopy

Jankowski

Reszke²,

Broekaert

2016

Encyclopedia of Analytical Chemistry

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The art and science of microwave plasma (MWP) optical and mass spectroscopy is briefly presented including very recent advances in the field up to 2015. The use of MWPs as radiation sources for optical emission (OES) and atomic fluorescence (AFS) spectroscopy and as atom reservoirs for atomic absorption (AAS) and cavity ringdown (CRDS) spectroscopy as well as ion sources for both elemental and molecular mass spectrometry (MS) is treated. Devices for producing both E‐type capacitively coupled microwave plasma (CMP)‐electrode and microwave‐induced plasma (MIP)‐electrodeless MWPs, including ICP‐like H‐type plasmas, are classified and discussed, in addition to techniques of their diagnostics, and results for the analytically relevant plasma parameters are presented. The means of generation of voluminous symmetrical plasmas and uses of microplasma devices are also presented with an effort to comment on general classification of microwave cavities. Further, the use of microwaves for boosting of glow discharges (GDs) and laser‐induced plasmas (LIBS) is treated along with other tandem sources. Methods for introduction of gaseous, liquid, and solid samples into the MWP are discussed. They include direct vapor sampling (DVS), chemical vapor generation (CVG) and hydride generation (HG) techniques, dry aerosol generation techniques (electrothermal vaporization (ETV), spark (SA) and laser ablation (LA) and continuous powder introduction (CPI)), and wet aerosol generation techniques using both solution and slurry nebulization. Special reference is made to coupling with gas chromatography (GC) and also with various separation techniques for liquids including high‐performance liquid chromatography (HPLC), supercritical fluid chromatography (SFC), and size‐exclusion chromatography (SEC). The analytical figures of merit in the case of OES with MIPs, CMPs, microwave plasma torch (MPT), MWP‐electrode sources including rotating‐field‐sustained plasma, and H‐type MWP as well as microplasmas are given. There are also described cases of atomic absorption and fluorescence with these sources. The developments in both elemental and molecular MS in the case of both cold and hot MWPs and in the case of various types of sample introduction techniques are discussed. Applications of MWP analytical spectroscopy are in the fields of biological, clinical, environmental, and industrial samples with special reference to multielement analysis, element speciation, on‐line monitoring, particle sizing, and direct solids analysis. A critical comparison of the methodology with other spectroscopic methods for the determination of the elements and their species is given.

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Generation of ultrahigh frequency air microplasma in a magnetic loop and effects of pulse modulation on operation

Cited by 11 publications

References 13 publications

Microplasmas ignited and sustained by microwaves

Microplasmas ignited and sustained by microwaves

Plasma ionization under simulated ambient Mars conditions for quantification of methane by mass spectrometry

Microwave Plasma Systems in Optical and Mass Spectroscopy

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