Optical emission, electron energy, density, wave magnetic field and spectrum measurements in a helicon plasma source

We have numerically studied how an actual confinement magnetostatic field affects power deposition in a helicon source. We have solved the wave propagation by means of two electromagnetic solvers, namely: (i) plaSma Padova Inhomogeneous Radial Electromagnetic solver (SPIREs), a mono-dimensional finite-difference frequency-domain code, and (ii) Advanced coDe for Anisotropic Media and ANTennas (ADAMANT), a full-wave three-dimensional tool based on the method of moments. We have computed the deposited power spectrum with SPIREs, power deposition profile with ADAMANT and the antenna impedance with both codes. First we have verified the numerical accuracy of both SPIREs and ADAMNT. Then, we have analysed two configurations of magnetostatic field, namely produced by Maxwell coils, and Helmholtz coils. For each configuration we have studied three cases: (i) low density $n=10^{17}~\text{m}^{-3}$ and low magnetic field $B_{0}=250$ G; (ii) medium density $n=10^{18}~\text{m}^{-3}$ and medium magnetic field $B_{0}=500$ G; (iii) high density $n=10^{19}~\text{m}^{-3}$ and high magnetic field $B_{0}=1000$ G. We have found that the Maxwell coil configuration does not produces significant changes in the deposited power phenomenon with respect to a perfectly uniform and axial magnetostatic field. While the Helmholtz coil configuration can lead to a power spectrum peaked near the axis of the discharge.

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Beam Plasma Characteristics of a Helicon Plasma Source Measured by a Spatially Resolved Optical Emission Spectroscope

IEEE Transactions on Plasma Science ◽

10.1109/tps.2020.3000245 ◽

2020 ◽

Vol 48 (7) ◽

pp. 2487-2494

Author(s):

Zun Zhang ◽

Kan Xie ◽

Huihui Wang ◽

Chang Tan ◽

Jiting Ouyang

Keyword(s):

Optical Emission ◽

Plasma Source ◽

Helicon Plasma ◽

Spatially Resolved ◽

Beam Plasma ◽

Plasma Characteristics

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Can the Local Bubble explain the radio background?

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab131 ◽

2021 ◽

Vol 502 (2) ◽

pp. 2807-2814

Author(s):

Martin G H Krause ◽

Martin J Hardcastle

Keyword(s):

Magnetic Field ◽

Energy Density ◽

Radio Emission ◽

Magnetic Energy ◽

Cosmic Ray ◽

Observational Constraints ◽

Local Bubble ◽

Magnetic Energy Density ◽

Magnetic Field Model ◽

Radio Background

ABSTRACT The ARCADE 2 balloon bolometer along with a number of other instruments have detected what appears to be a radio synchrotron background at frequencies below about 3 GHz. Neither extragalactic radio sources nor diffuse Galactic emission can currently account for this finding. We use the locally measured cosmic ray electron population, demodulated for effects of the Solar wind, and other observational constraints combined with a turbulent magnetic field model to predict the radio synchrotron emission for the Local Bubble. We find that the spectral index of the modelled radio emission is roughly consistent with the radio background. Our model can approximately reproduce the observed antenna temperatures for a mean magnetic field strength B between 3 and 5 nT. We argue that this would not violate observational constraints from pulsar measurements. However, the curvature in the predicted spectrum would mean that other, so far unknown sources would have to contribute below 100 MHz. Also, the magnetic energy density would then dominate over thermal and cosmic ray electron energy density, likely causing an inverse magnetic cascade with large variations of the radio emission in different sky directions as well as high polarization. We argue that this disagrees with several observations and thus that the magnetic field is probably much lower, quite possibly limited by equipartition with the energy density in relativistic or thermal particles (B = 0.2−0.6 nT). In the latter case, we predict a contribution of the Local Bubble to the unexplained radio background at most at the per cent level.

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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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Merits of microwave plasmas for optical emission spectrometry – characterization of an axially viewed microwave-sustained, inductively coupled, atmospheric-pressure plasma (MICAP)

Journal of Analytical Atomic Spectrometry ◽

10.1039/d0ja00293c ◽

2020 ◽

Vol 35 (10) ◽

pp. 2369-2377

Author(s):

Helmar Wiltsche ◽

Matthias Wolfgang

Keyword(s):

Atmospheric Pressure ◽

Atmospheric Pressure Plasma ◽

Optical Emission ◽

Plasma Source ◽

Optical Emission Spectrometry ◽

Emission Spectrometry ◽

Icp Oes ◽

Microwave Plasmas ◽

Inductively Coupled

The MICAP is a microwave driven plasma source employing nitrogen as the plasma gas. In this work we compare LODs and LOQs obtained in axial viewing with those obtained by ICP-OES and evaluate the effect of air instead of nitrogen as the plasma gas.

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