The average magnetic field draping and consistent plasma properties of the Venus magnetotail

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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Non-damping oscillations at flaring loops

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832991 ◽

2018 ◽

Vol 617 ◽

pp. A86 ◽

Cited By ~ 11

Author(s):

D. Li ◽

D. Yuan ◽

Y. N. Su ◽

Q. M. Zhang ◽

W. Su ◽

...

Keyword(s):

Magnetic Field ◽

Line Width ◽

Line Emission ◽

Flux Rope ◽

Doppler Velocity ◽

Narrow Slit ◽

Plasma Properties ◽

Spectral Window ◽

Peak Intensity ◽

The Magnetic Field

Context. Quasi-periodic oscillations are usually detected as spatial displacements of coronal loops in imaging observations or as periodic shifts of line properties (i.e., Doppler velocity, line width and intensity) in spectroscopic observations. They are often applied for remote diagnostics of magnetic fields and plasma properties on the Sun. Aims. We combine the imaging and spectroscopic measurements of available space missions, and investigate the properties of non-damping oscillations at flaring loops. Methods. We used the Interface Region Imaging Spectrograph (IRIS) to measure the spectrum over a narrow slit. The double-component Gaussian fitting method was used to extract the line profile of Fe XXI 1354.08 Å at the “O I” spectral window. The quasi-periodicity of loop oscillations were identified in the Fourier and wavelet spectra. Results. A periodicity at about 40 s is detected in the line properties of Fe XXI 1354.08 Å, hard X-ray emissions in GOES 1−8 Å derivative, and Fermi 26−50 keV. The Doppler velocity and line width oscillate in phase, while a phase shift of about π/2 is detected between the Doppler velocity and peak intensity. The amplitudes of Doppler velocity and line width oscillation are about 2.2 km s−1 and 1.9 km s−1, respectively, while peak intensity oscillates with amplitude at about 3.6% of the background emission. Meanwhile, a quasi-period of about 155 s is identified in the Doppler velocity and peak intensity of the Fe XXI 1354.08 Å line emission, and AIA 131 Å intensity. Conclusions. The oscillations at about 40 s are not damped significantly during the observation; this might be linked to the global kink modes of flaring loops. The periodicity at about 155 s is most likely a signature of recurring downflows after chromospheric evaporation along flaring loops. The magnetic field strengths of the flaring loops are estimated to be about 120−170 G using the magnetohydrodynamic seismology diagnostics, which are consistent with the magnetic field modeling results using the flux rope insertion method.

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A 4 × 4 array multichannel magnetic stimulation system using submillimeter sized planar square spiral coils: The spatial distribution of electromagnetic field

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-210139 ◽

2022 ◽

pp. 1-18

Author(s):

Lei Tian ◽

Limei Song ◽

Yu Zheng ◽

Jinhai Wang

Keyword(s):

Magnetic Field ◽

Electromagnetic Field ◽

Spatial Distribution ◽

Field Strength ◽

Electric Field ◽

Magnetic Stimulation ◽

Spiral Coil ◽

Average Magnetic Field ◽

Stimulation System ◽

Field Strengths

Multi-coil magnetic stimulation has advantages over single-coil magnetic stimulation, such as more accurate targeting and larger stimulation range. In this paper, a 4 × 4 array multichannel magnetic stimulation system based on a submillimeter planar square spiral coil is proposed. The effects of multiple currents with different directions on the electromagnetic field strength and the focusing zone of the array-structured magnetic stimulation system are studied. The spatial distribution characteristics of the electromagnetic field are discussed. In addition, a method is proposed that can predict the spatial distributions of the electric and magnetic fields when currents in different directions are applied to the array-structured magnetic stimulation system. The study results show that in the section of z = 2 μm, the maximum and average magnetic field strengths of the array-structured magnetic stimulation system are 6.39 mT and 2.68 mT, respectively. The maximum and average electric field strengths are 614.7 mV/m and 122.82 mV/m, respectively, where 84.39% of the measured electric field values are greater than 73 mV/m. The average magnetic field strength of the focusing zone, i.e., the zone in between the two coils, is 3.38 mT with a mean square deviation of 0.18. Therefore, the array-structured multi-channel magnetic stimulation system based on a planar square spiral coil can have a small size of 412 μm × 412 μm × 1.7 μm, which helps improving the spatial distribution of electromagnetic field and increase the effectiveness of magnetic stimulation. The main contribution of this paper is a method for designing multichannel micro-magnetic stimulation devices.

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Survey of Jupiter’s Plasma Disk from Juno Observations

10.5194/egusphere-egu21-989 ◽

2021 ◽

Author(s):

Fran Bagenal ◽

Ezra Huscher ◽

Robert Wilson ◽

Frederic Allegrini ◽

Robert Ebert

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Magnetic Field Strength ◽

Plasma Sheet ◽

Radial Distance ◽

Regular Structure ◽

Plasma Properties ◽

Density Distributions ◽

Jovian System ◽

Structure Density

<p>Using 30 inbound passes through the Jovian system, we combine measurements from the fields and particles instruments on the Juno spacecraft to survey the properties of Jupiter's plasma disk. Juno's orbit is particularly useful for exploring the variation in plasma conditions with latitude as well as radial distance (from ~10 to ~50 RJ). We present basic plasma properties (composition, density, temperature, velocity, magnetic field strength) to make maps of the plasma environment. Also show that on some of the 53-day orbits the plasma sheet has regular structure (density having roughly Gaussian distribution with latitude and decreasing with distance) but there are also highly irregular orbits with low or erratic density distributions.</p>

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