Plasma asymmetry due to the magnetic filter in fusion-type negative ion sources: Comparisons between two and three-dimensional particle-in-cell simulations

2014 ◽  
Vol 21 (7) ◽  
pp. 073512 ◽  
Author(s):  
G. Fubiani ◽  
J. P. Boeuf
Keyword(s):  
Three Dimensional ◽  
Ion Sources ◽  
Negative Ion ◽  
Particle In Cell ◽  
Magnetic Filter ◽  
Fusion Type

scholarly journals Concepts of magnetic filter fields in powerful negative ion sources for fusion

2016 ◽  
Vol 87 (2) ◽  
pp. 02B315 ◽  
Author(s):  
W. Kraus ◽  
U. Fantz ◽  
B. Heinemann ◽  
D. Wünderlich
Keyword(s):  
Ion Sources ◽  
Negative Ion ◽  
Magnetic Filter

scholarly journals Particle-In-Cell Simulations of the Cassini Spacecraft’s Interaction with Saturn’s Ionosphere during the Grand Finale

2021 ◽  
Author(s):  
Zeqi Zhang ◽  
Ravindra T Desai ◽  
Yohei Miyake ◽  
Hideyuki Usui ◽  
Oleg Shebanits
Keyword(s):  
Three Dimensional ◽  
Potential Gradient ◽  
Ion Concentration ◽  
Negative Ion ◽  
High Electron ◽  
Free Electrons ◽  
Field Orientation ◽  
Particle In Cell ◽  
Spacecraft Potential ◽  
Charged Ions

Abstract A surprising and unexpected phenomenon observed during Cassini’s Grand Finale was the spacecraft charging to positive potentials in Saturn’s ionosphere. Here, the ionospheric plasma was depleted of free electrons with negatively charged ions and dust accumulating up to over 95 % of the negative charge density. To further understand the spacecraft-plasma interaction, we perform a three dimensional Particle-In-Cell study of a model Cassini spacecraft immersed in plasma representative of Saturn’s ionosphere. The simulations reveal complex interaction features such as electron wings and a highly structured wake containing spacecraft-scale vortices. The results show how a large negative ion concentration combined with a large negative to positive ion mass ratio is able to drive the spacecraft to the observed positive potentials. Despite the high electron depletions, the electron properties are found as a significant controlling factor for the spacecraft potential together with the magnetic field orientation which induces a potential gradient directed across Cassini’s asymmetric body. This study reveals the global spacecraft interaction experienced by Cassini during the Grand Finale and how this is influenced by the unexpected negative ion and dust populations.

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