Numerical 3D Modeling: Microwave Plasma Torch at Intermediate Pressure

This study represents a self-consistent three-dimensional (3D) fluid plasma model coupled with Maxwell equations at an intermediate pressure between 1000 and 5000 Pa. The model was established using the finite element method to analyze the effects of time–space characteristics, which is the variation of plasma parameters with time and the 3D spatial distribution of plasma parameters in the plasma torch at various times. The numerical modeling was demonstrated in three different stages, where the growth of electron density is associated with time. From the distribution characteristics of molecular ions, it can be concluded that they are distributed mainly at the port of the quartz tube of the torch, which is larger than the center of the tube. The density ratio of molecular ion to electron is decreased because of the reduction of pressure and distance, which has been calculated from the port to the center of the quartz tube. The analysis of microwave plasma parameters indicated that intermediate pressure is useful for modeling and plasma source designing, especially for carbon dioxide conversion.

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Langmuir Probe Diagnostics with Optical Emission Spectrometry (OES) for Coaxial Line Microwave Plasma

Applied Sciences ◽

10.3390/app10228117 ◽

2020 ◽

Vol 10 (22) ◽

pp. 8117

Author(s):

Chi Chen ◽

Wenjie Fu ◽

Chaoyang Zhang ◽

Dun Lu ◽

Meng Han ◽

...

Keyword(s):

Electron Temperature ◽

Langmuir Probe ◽

Microwave Plasma ◽

Optical Emission ◽

Coaxial Line ◽

Plasma Source ◽

Optical Emission Spectrometry ◽

Emission Spectrometry ◽

Plasma Parameters ◽

Current Voltage

The Langmuir probe is a feasible method to measure plasma parameters. However, as the reaction progresses in the discharged plasma, the contamination would be attached to the probe surface and lead to a higher incorrect electron temperature. Then, the electron density cannot be obtained. This paper reports a simple approach to combining the Langmuir probe and the optical emission spectrometry (OES), which can be used to obtain the electron temperature to solve this problem. Even the Langmuir probe is contaminative, the probe current–voltage (I–V) curve with the OES spectra also gives the approximate electron temperature and density. A homemade coaxial line microwave plasma source driven by a 2.45 GHz magnetron was adopted to verify this mothed, and the electron temperature and density in different pressure (40–80 Pa) and microwave power (400–800 W) were measured to verify that it is feasible.

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Magnetothermodynamics: measurements of the thermodynamic properties in a relaxed magnetohydrodynamic plasma

Journal of Plasma Physics ◽

10.1017/s0022377818000156 ◽

2018 ◽

Vol 84 (1) ◽

Cited By ~ 9

Author(s):

M. Kaur ◽

L. J. Barbano ◽

E. M. Suen-Lewis ◽

J. E. Shrock ◽

A. D. Light ◽

...

Keyword(s):

Laboratory Experiments ◽

Equations Of State ◽

Three Dimensional ◽

Laser Interferometry ◽

Plasma Source ◽

Magnetized Plasma ◽

Ion Heating ◽

Plasma Parameters ◽

Doppler Spectroscopy ◽

End Wall

We have explored the thermodynamics of compressed magnetized plasmas in laboratory experiments and we call these studies ‘magnetothermodynamics’. The experiments are carried out in the Swarthmore Spheromak eXperiment device. In this device, a magnetized plasma source is located at one end and at the other end, a closed conducting can is installed. We generate parcels of magnetized plasma and observe their compression against the end wall of the conducting cylinder. The plasma parameters such as plasma density, temperature and magnetic field are measured during compression using HeNe laser interferometry, ion Doppler spectroscopy and a linear ${\dot{B}}$ probe array, respectively. To identify the instances of ion heating during compression, a PV diagram is constructed using measured density, temperature and a proxy for the volume of the magnetized plasma. Different equations of state are analysed to evaluate the adiabatic nature of the compressed plasma. A three-dimensional resistive magnetohydrodynamic code (NIMROD) is employed to simulate the twisted Taylor states and shows stagnation against the end wall of the closed conducting can. The simulation results are consistent to what we observe in our experiments.

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Characterization of high microwave power atmospheric pressure plasma torch

Canadian Journal of Physics ◽

10.1139/cjp-2017-0751 ◽

2018 ◽

Vol 96 (7) ◽

pp. 851-854

Author(s):

B. Turkyilmaz ◽

D. Mansuroglu ◽

I.U. Uzun-Kaymak

Keyword(s):

Microwave Power ◽

Atmospheric Pressure ◽

Plasma Torch ◽

Microwave Plasma ◽

Atmospheric Pressure Plasma ◽

Optical Emission ◽

Spectral Lines ◽

Plasma Parameters ◽

Boltzmann Plot ◽

Plasma Torches

An atmospheric pressure microwave plasma torch operating at 2.45 GHz frequency using a surfaguide waveguide fed by argon gas at a constant rate is characterized at various microwave power settings. Coarse optical emission spectroscopy technique is used to diagnose the plasma parameters. The Boltzmann plot method is implemented to measure the electron temperature. Using the Doppler shift of the strong argon atomic spectral lines, the plasma velocity is determined. These results are in good agreement with earlier studies conducted on similar microwave plasma torches at a lower power setting. In this study, we exceed the previous power limitations observed in earlier studies and scan the microwave power in increments up to 2 kW.

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Compressive behaviours of octet-truss lattices

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220913586 ◽

2020 ◽

Vol 234 (16) ◽

pp. 3257-3269 ◽

Cited By ~ 1

Author(s):

Yifan Li ◽

Huaiyuan Gu ◽

Martyn Pavier ◽

Harry Coules

Keyword(s):

Failure Modes ◽

Density Ratio ◽

Three Dimensional ◽

Compressive Load ◽

High Strength ◽

Detailed Comparison ◽

Compressive Response ◽

Beam Elements ◽

Structural Applications ◽

Octet Truss

Octet-truss lattice structures can be used for lightweight structural applications due to their high strength-to-density ratio. In this research, octet-truss lattice specimens were fabricated by stereolithography additive manufacturing with a photopolymer resin. The mechanical properties of this structure have been examined in three orthogonal orientations under the compressive load. Detailed comparison and description were carried out on deformation mechanisms and failure modes in different lattice orientations. Finite element models using both beam elements and three-dimensional solid elements were used to simulate the compressive response of this structure. Both the load reaction and collapse modes obtained in simulations were compared with test results. Our results indicate that three-dimensional continuum element models are required to accurately capture the behaviour of real trusses, taking into account the effects of finite-sized beams and joints.

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Long-pulse plasma source for SMOLA helical mirror

Journal of Plasma Physics ◽

10.1017/s0022377821000131 ◽

2021 ◽

Vol 87 (2) ◽

Author(s):

Ivan A. Ivanov ◽

V. O. Ustyuzhanin ◽

A. V. Sudnikov ◽

A. Inzhevatkina

Keyword(s):

Magnetic Field ◽

Gas Flow ◽

Supply Voltage ◽

Hydrogen Plasma ◽

Plasma Source ◽

Lanthanum Hexaboride ◽

Plasma Stream ◽

Plasma Parameters ◽

Plasma Properties ◽

Plasma Gun

A plasma gun for forming a plasma stream in the open magnetic mirror trap with additional helicoidal field SMOLA is described. The plasma gun is an axisymmetric system with a planar circular hot cathode based on lanthanum hexaboride and a hollow copper anode. The two planar coils are located around the plasma source and create a magnetic field of up to 200 mT. The magnetic field forms the magnetron configuration of the discharge and provides a radial electric insulation. The source typically operates with a discharge current of up to 350 A in hydrogen. Plasma parameters in the SMOLA device are Ti ~ 5 eV, Te ~ 5–40 eV and ni ~ (0.1–1) × 1019 m−3. Helium plasma can also be created. The plasma properties depend on the whole group of initial technical parameters: the cathode temperature, the feeding gas flow, the anode-cathode supply voltage and the magnitude of the cathode magnetic insulation.

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Electrostatic wave breaking limit in a cold electronegative plasma with non-Maxwellian electrons

Scientific Reports ◽

10.1038/s41598-021-85228-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

I. S. Elkamash ◽

I. Kourakis

Keyword(s):

Wave Breaking ◽

Density Ratio ◽

Negative Ions ◽

First Integral ◽

Energy Balance Equation ◽

Plasma Parameters ◽

Ion Density ◽

Electrostatic Wave ◽

Nonthermal Electrons ◽

Electronegative Plasma

AbstractA one-dimensional multifluid hydrodynamic model has been adopted as basis for an investigation of the role of suprathermal electrons on the wave breaking amplitude limit for electrostatic excitations propagating in an electronegative plasma. A three-component plasma is considered, consisting of two inertial cold ion populations of opposite signs, evolving against a uniform background of (non-Maxwellian) electrons. A kappa-type (non-Maxwellian) distribution function is adopted for the electrons. By employing a traveling wave approximation, the first integral for the fluid-dynamical system has been derived, in the form of a pseudo-energy balance equation, and analyzed. The effect of intrinsic plasma parameters (namely the ion density ratio, the ion mass ratio, and the superthermal index of the nonthermal electrons) on the wave breaking amplitude limit is explored, by analyzing the phase space topology of the associated pseudopotential function. Our results are relevant to particle acceleration in Space environments and to recent experiments based on plasma-based accelerator schemes, where the simultaneous presence of negative ions and nonthermal electrons may be observed.

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