The role of second‐order radial density gradient for helicon power absorption

Wang, Runlong; Chang, Lei; Hu, Xinyue; Ping, Lanlan; Hu, Ning; Wu, Xianming; Yao, Jianyao; Sun, Xinfeng; Zhang, Tianping

doi:10.1002/ctpp.201900032

Cited by 5 publications

(4 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is consistent with the experimental observation that the discharge transits from blue-colour mode to blue-core mode [9]. The decreased power for shrunk density profiles implies that certain magnitude of plasma density near edge is beneficial for power coupling, which also agrees with previous studies [40,41,42,43,44]. More interestingly, we find that the power deposition is hollow in radius for all field strengths and its peak moves closer to axis when the field strength increases.…”

Section: Power Depositionsupporting

confidence: 92%

See 1 more Smart Citation

Wave propagation and power deposition in blue-core helicon plasma

Chang¹,

Caneses²,

Thakur³

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

The wave propagation and power deposition in blue-core helicon plasma are computed referring to recent experiments. It is found that the radial profile of wave electric field peaks off-axis during the blue-core formation, and the location of this peak is very close to that of particle transport barrier observed in experiment; the radial profile of wave magnetic field shows multiple radial modes inside the bluecore column, which is consistent with the experimental observation of coherent high m modes through Bessel function. The axial profiles of wave field indicate that, once the blue-core mode has been achieved, waves can only propagate inside the formed column with distinct phase compared to that outside. The wave energy distribution shows a clear and sharp boundary at the edge of blue-core column, besides which periodic structures are observed and the axial periodicity inside is nearly twice that outside. The dispersion relation inside the blue-core column exhibits multiple modes, a feature of resonant cavity that selects different modes during frequency variation, while the dispersion relation outside gives constant wave number with changed frequency. The power deposition appears to be off-axis in the radial direction and periodic in the axial direction, and mostly inside the blue-core column. Analyses based on steplike function theory and introduced blue-core constant provide consistent results. The equivalence of blue-core column to optical fiber for electromagnetic communication is also explored and inspires a novel application of helicon plasma, which may be one of the most interesting findings of present work.

show abstract

Section: Power Depositionsupporting

confidence: 92%

“…This could be attributed to the plasma density near edge which is too low to efficiently couple the power from antenna into core. This critical role of edge density has been also claimed by other studies [40,41,42,43,44].…”

Section: Step-like Function Theorysupporting

confidence: 81%

Wave propagation and power deposition in blue-core helicon plasma

Chang¹,

Caneses²,

Thakur³

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is commented that (a-c) are generic phenomena for plasma discharge and insufficient to support the remarkable ionisation rate and high density of helicon sources, and more attention should be paid to (d-e) which involves the critical parameter of confining magnetic field that promotes the density jump from inductively coupled plasma to helicon mode; further, (4) and ( 5) rely on density magnitude and density gradient, respectively, and optimum discharge may be achieved when the required density magnitude comes across with the largest density gradient at the same location. Then, the sign (positive or negative) and zero-crossing position of second-order density gradient are shown to effect the power absorption profile significantly, consistent with (5) [32][33][34]. Moreover, it is suggested that the power deposition profile could be shaped by designing the antenna of particular geometry to excite the required axial current distribution, considering their resemblance.…”

Section: Introductionsupporting

confidence: 54%

First Helicon Plasma Physics and Applications Workshop

2022

Self Cite

View full text Add to dashboard Cite

The First Helicon Plasma Physics and Applications Workshop was held on September 23−24, 2021, through Zoom Cloud Meeting, instead of in an on-site gathering, due to the COVID-19 pandemic. It was convened by Rod Boswell (IOC) and Guangnan Luo (LOC), and organised by Lei Chang’s group. The workshop attracted 110 registrations and ∼100 online audiences from ∼30 affiliations. There were 33 presentations covering the various fundamental physics of helicon plasma and its applications to space electric propulsion, material processing, and magnetic confinement fusion. This paper highlights the presentations, discussions, and perspectives given in the workshop, serving as reference for the helicon community.

show abstract

“…In this paper, the influence of temperature and pressure gradients on power deposition, electric field intensity, and current density under two different plasma density distributions is studied by using HELIC code. [21][22][23] Compared with other codes (such as EMS code, ANTENA2 code, SPIREs code, ANAMANT code), HELIC code uses specific boundary conditions to solve six radially coupled differential equations to obtain two independent waves (H wave and TG wave). It is much faster than dividing the nonuniform plasma into layers and matching boundary conditions on each interface.…”

Section: Introductionmentioning

confidence: 99%

Influence of temperature and pressure gradient on power deposition and field pattern in High Magnetic field Helicon eXperiment

Zhou,

Huang,

2024

Contrib. Plasma Phys

View full text Add to dashboard Cite

Based on High Magnetic field Helicon eXperiment, considering the parabolic distribution and Gaussian distribution of radial plasma density, HELIC code was used to study the influence of temperature and pressure gradient on power deposition, electric field, and current density of Helicon Wave Plasma. Three different gradients (positive, negative, and zero gradient) were selected. The results show that positive temperature gradient is beneficial to increase the relative absorption power at the center of plasma. Compared with negative and zero pressure gradients, positive pressure gradient increases the relative absorption power and weakens the current density at the center of plasma, and increases the electric field intensity at the edge of plasma. Larger edge heating will cause the relative absorption power at edge to rise rapidly, which is not conducive to the coupling at the center of plasma. In practical experiments, it is particularly important to reduce the heating effect at edge by cooling the antenna itself. Three different gradients of temperature and pressure have little effect on electric field intensity and current density in plasma, and the variation trend is basically similar, which proves the stability of the antenna mode: m = 1.

show abstract

The role of second‐order radial density gradient for helicon power absorption

Cited by 5 publications

References 29 publications

Wave propagation and power deposition in blue-core helicon plasma

Wave propagation and power deposition in blue-core helicon plasma

First Helicon Plasma Physics and Applications Workshop

Influence of temperature and pressure gradient on power deposition and field pattern in High Magnetic field Helicon eXperiment

Contact Info

Product

Resources

About