Properties of the electrostatically driven helical plasma state
- Tibbar Plasma Technologies, Los Alamos, NM (United States)
A novel plasma state has been found [Akçay et al., Phys. Plasmas 24, 052503 (2017)] in the presence of a uniform applied axial magnetic field in periodic cylindrical geometry. This state is driven by external electrostatic fields provided by helical electrodes with a ($m=1,n=1$) (helical) symmetry where $$m$$ and $$n$$ represent the poloidal and axial harmonics. The resulting plasma is a function of the cylinder radius $$r < r_w$$ and helical angle $u=mθ-nζ$, where θ is the poloidal angle, and $ζ=z/R$ is the normalized axial coordinate in the context of a periodic cylinder. In this reference, the strongly driven form of the state was found to have a strong axial mean current density, with a mean-field line safety factor $$q_0(r)$$ just above the pitch of the electrodes m/n=1 in the interior, where the plasma is nearly force-free. However, at the edge the current density has a component perpendicular to the magnetic field B. This perpendicular current density drives nearly Alfvénic helical plasma flows, a notable feature of these states. This state is being studied for its possible application in $DC$ electrical transformers. We present results on several issues of importance for these applications: the transient leading to the steady state; the twist and writhe of the field lines and their relation with the current density; the properties of the current density streamlines and length of the current density lines connected to the electrodes; the sensitivity to changes in the velocity boundary conditions; the effect of varying the radial resistivity profile; and the effects of a concentrated electrode potential
- Research Organization:
- Tibbar Plasma Technologies, Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Advanced Research Projects Agency - Energy (ARPA-E)
- Grant/Contract Number:
- AR0000677
- OSTI ID:
- 1524593
- Alternate ID(s):
- OSTI ID: 1419704
- Journal Information:
- Physics of Plasmas, Vol. 25, Issue 2; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Electrostatically driven helical plasma state
Final Technical Report