The role of ion magnetization on plasma generation in a magnetic nozzle rf device

Filleul, Félicien; Caldarelli, Antonella; Boswell, Rod; Charles, Christine; Rattenbury, N. J.; Cater, John

doi:10.1007/s44205-022-00021-y

Cited by 10 publications

(8 citation statements)

References 27 publications

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“…The antenna-magnetic mirror separation of z B = 30 cm was found to maximise the plasma generation under the solenoids in the converging-diverging plasma column when B 0 is greater than a threshold value of 250 G. For B 0 below this threshold, the maximum achieved density is reduced and the axial density profile is bimodal with one maximum under the antenna and one under the solenoids. It was shown that these features and the plasma parameters absolute values were closely maintained when changing the antenna and radiofrequency to a single-loop antenna driven at 27.12 MHz [28,37].…”

Section: Plasma Discharge Characteristicsmentioning

confidence: 92%

“…Argon I and II emissions at 750.4 nm and 488 nm are measured with a previously described arrangement made out of two 10 nm narrow-band-pass filters and a calibrated CMOS sensor [37]. A feature of optical emission spectroscopy (OES) is that the intensity of emission lines can be interpreted in terms of the density and temperature of the particles contributing to their excitation.…”

Section: Plasma Diagnosticsmentioning

confidence: 99%

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Helicon waves in a converging-diverging magnetoplasma

Filleul,

Caldarelli,

Takahashi

et al. 2023

Plasma Sources Sci. Technol.

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Waves propagating along a converging-diverging rf magnetoplasma having the characteristics of a bounded m = 0 helicon mode are reported and characterised. The discharge features a 30 cm separation between the region of radiofrequency energy deposition by a single loop antenna and the region of maximum magnetic ﬁeld applied by a pair of coils. With 200 W of rf input power, up to a ﬁve-fold increase in axial plasma density between the antenna and the magnetic mirror throat is observed together with an Ar II blue-mode. Two dimensional B-dot probe measurements show that the rf magnetic ﬁelds are closely guided by the converging-diverging geometry. The wave is characterised as a m = 0 mode satisfying the helicon dispersion relation on-axis with radial boundary conditions approximately matching the radii of the plasma column. Analysis of the wave phase velocity and wave axial damping failed to identify collisionless or collisional wave-plasma coupling mechanisms. Instead, the wave axial amplitude variations can be explained by local wave resonances and possible reﬂections from localised rapid changes of the refractive index. A Venturi-like effect owing to the funnel-shaped magnetoplasma and conservation of the wave energy may also explain some level of amplitude variations.

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Section: Plasma Discharge Characteristicsmentioning

confidence: 92%

Section: Plasma Diagnosticsmentioning

confidence: 99%

Helicon waves in a converging-diverging magnetoplasma

Filleul,

Caldarelli,

Takahashi

et al. 2023

Plasma Sources Sci. Technol.

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“…The data used in this study has been acquired using Moa 31 , a radio-frequency plasma reactor that is an expansion of Huia 32,33 . It consists of a 150 cm long, 9 cm inner diameter borosilicate glass tube plasma source connected to a 70 cm long, 50 cm diameter steel expansion chamber hosting the pumping system and the pressure gauges.…”

Section: A Apparatusmentioning

confidence: 99%

“…5. tions create an inductively coupled plasma exhibiting a symmetrical single peaked axial plasma density gradient ranging from 10 12 cm −3 under the solenoids to 10 10 cm −3 at the extremities of the glass tube 32,33,53 . The LP was placed on axis halfway between the antenna and the solenoids.…”

Section: Electron-energy Probability Function (Eepf)mentioning

confidence: 99%

Data Processing Techniques for Ion and Electron Energy Distribution Functions

Caldarelli¹,

Filleul²,

Boswell³

et al. 2022

Preprint

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Retarding field energy analyzers and Langmuir probes are routinely used to obtain ion and electron energy distribution functions (IEDF, EEDF). These typically require knowledge of the first and second derivatives of the I-V characteristics, both of which can be obtained in various ways. This poses challenges inherent to differentiating noisy signals, a frequent problem with electric-probe plasma diagnostics. A brief review of commonly used analog and numerical filtering and differentiation techniques is presented, together with their application on experimental data collected in a radio-frequency plasma. The application of each method is detailed with regards to the obtained IEDF and EEDF, the deduced plasma parameters, dynamic range, energy resolution and signal distortion.

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“…the location of plasma excitation coincides with the magnetic nozzle throat), the experiments presented herein are conducted in an RF plasma device in which the antenna and the coils are not placed on the same axial location (see figure 3). Studies with a similar experimental design have been carried out by [16,21,29,[31][32][33][34]. In this configuration, the plasma is created remotely with respect to the magnetic nozzle throat.…”

Section: Introductionmentioning

confidence: 99%

Effects of magnetic nozzle strength and orientation on radio-frequency plasma expansion

Caldarelli

Filleul

Charles

et al. 2023

Plasma Sources Sci. Technol.

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To improve the efficiency of radio-frequency magnetic nozzle plasma thrusters, it is important to better understand the coupling between plasma expansion and a convergent-divergent magnetic field. This study explores the effects of magnetic field strength and orientation on plasma expansion in a magnetic nozzle.Two-dimensional measurements of the plasma characteristics obtained both in the source and in the expansion region are presented to investigate the influence of magnetic field strength on the formation of high-density conics in a symmetric magnetic nozzle. The measurements are repeated in a deflected magnetic nozzle using a novel magnetic steering system. Measurements of the ion saturation current and floating potential profiles are used respectively to qualitatively assess the plasma density distribution and the presence of high-energy electrons for the magnetic field configurations analysed. In the symmetric magnetic nozzle configuration, it is observed that the ion saturation current peaks on axis in the plasma source, but downstream of the nozzle throat, a double-peaked hollow profile is observed for all cases studied. The location of the high-density conics structure matches the most radial field lines that intersect the antenna and can freely expand downstream outside the source. Negative values of the floating potential are measured in the same peripheral regions, which could be a sign of the presence of high-energy electrons. When the magnetic field is deflected, the ion saturation current profile shows only a single peak centred around the bent field line that reconnects to the antenna. Again, a region of negative floating potential is measured at the location of the maximum ion current. Thus, it is shown how, independent of magnetic field strength and orientation, the magnetic field lines interacting with the antenna dictate the local plasma profiles downstream from the magnetic nozzle.

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The role of ion magnetization on plasma generation in a magnetic nozzle rf device

Cited by 10 publications

References 27 publications

Helicon waves in a converging-diverging magnetoplasma

Helicon waves in a converging-diverging magnetoplasma

Data Processing Techniques for Ion and Electron Energy Distribution Functions

Effects of magnetic nozzle strength and orientation on radio-frequency plasma expansion

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