Properties of lower hybrid waves

Verdon, Alix; Cairns, Iver H.; Melrose, D. B.; Robinson, P. A.

doi:10.1017/s1743921309029871

Cited by 6 publications

(5 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This, in turn, alters the spectrum of waves with which the lower hybrid waves can interact, on both electron and ion scales (Liu, Chen & Ma 2021). Lower hybrid waves can efficiently transfer energy from the perpendicular motions of ions to the parallel motions of electrons or vice versa, either accelerating particles or heating them (Verdon et al 2008). What our results indicate is that gravity (through gravitomagnetic contributions to the lower hybrid wave mode) can play a non-negligible role in this energy transfer mechanism in ion and electron length scales, which will be explored later in detail.…”

Section: Discussionmentioning

confidence: 99%

Hybrid electrostatic waves in linearized gravity

Bhattacharjee,

Stark

2024

J. Plasma Phys.

View full text Add to dashboard Cite

Linearized gravity around a rotating black hole or compact object introduces the concept of a gravitomagnetic field, which originates from the matter–current in the rotating object. Plasma in proximity to this object is subsequently subjected to motion guided by this gravitomagnetic term (where mass serves as the effective charge) in addition to the conventional magnetic field. Such an interplay of fields complicates the accessible plasma waves of the system and thus merits exploration to delineate this interplay, to identify any observable signatures of the gravitomagnetic field in weakly magnetized systems, and to motivate future numerical work in a fully relativistic setting where the effects may be stronger. In this work we analyse the dispersion of the upper and lower hybrid electrostatic waves in a plasma immersed in both magnetic and gravitomagnetic fields. In particular, we discuss the effective augmentation or cancellation of the two fields under the right conditions for the upper hybrid wave. In contrast, the lower hybrid wave experiences a frequency up-shift from the gravitomagnetic field regardless of whether it is parallel or antiparallel to the magnetic field for the studied field strengths.

show abstract

Section: Discussionmentioning

confidence: 99%

Hybrid electrostatic waves in linearized gravity

Bhattacharjee,

Stark

2024

J. Plasma Phys.

View full text Add to dashboard Cite

show abstract

“…Moreover, we adopt the approximation that they can be treated as a cold unmagnetized fluid. Although recent analysis suggests that finite ion Larmor radius effects might be important for LH waves in some range of plasma parameters [78], this is not the case for LH propagating in the peripheral region of tokamak plasmas. The current density of the plasma ions of species j with charge q j and mass m j is given by: To compare our results with previous analysis, we consider two limiting cases.…”

Section: Hf(1) Ementioning

confidence: 96%

Nonlinear lower hybrid wave equations in collisional tokamak plasmas

Castaldo,

Napoli

2024

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

. A new set of coupled integro-differential nonlinear lower hybrid (LH) wave equations is derived in the framework of a kinetic theory coupled to the Maxwell equations to study the parametric instabilities (PI) produced by LH waves in collisional tokamak plasma. Previous models of nonlinear LH wave equations have been significantly improved. The wave equations derived overcome the limits and the incorrectness of the standard theory of the PI in inhomogeneous plasma. They allow treating the full spectrum in parallel and poloidal wavenumber of the coupled LH power wave, diffraction effects and possible cascade phenomena, which are elements of the nonlinear LH physics ignored in the standard PI theory. Numerical solutions of the new nonlinear LH wave equations are proposed. The relevant LH frequency spectra produced by PI are calculated, exhibiting characteristic features of PI observed in LH experiments. It is shown that the LH sideband amplification can be overestimated by orders of magnitude by the standard theory of PI. A benchmark of the new model is provided for spatially homogeneous plasmas. The role of the collisions for PI has been assessed. We demonstrate that previous analysis significantly overestimated their stabilization effect.

show abstract

“…Lower-hybrid waves have been analyzed in uniformly magnetized plasma [45,46]. They trap electrons magnetically and the trapped electrons confine the ions electrically.…”

Section: Two-dimensional Simulations 31 a Comparison Of The Boundary ...mentioning

confidence: 99%

PIC simulations of stable surface waves on a subcritical fast magnetosonic shock front

et al. 2023

View full text Add to dashboard Cite

We study with particle-in-cell (PIC) simulations the stability of fast magnetosonic shocks. They expand across a collisionless plasma and an orthogonal magnetic field that is aligned with one of the directions resolved by the 2D simulations. The shock speed is 1.6 times the fast magnetosonic speed when it enters a layer with a reduced density of mobile ions, which decreases the shock speed by up to 15\% in 1D simulations. In the 2D simulations, the density of mobile ions in the layer varies sinusoidally perpendicularly to the shock normal. We resolve one sine period. This variation only leads to small changes in the shock speed evidencing a restoring force that opposes a shock deformation. As the shock propagates through the layer, the ion density becomes increasingly spatially modulated along the shock front and the magnetic field bulges out where the mobile ion density is lowest. The perturbed shock eventually reaches a steady state. Once it leaves the layer, the perturbations of the ion density and magnetic field oscillate along its front at a frequency close to the lower-hybrid frequency; the shock is mediated by a standing wave composed of obliquely propagating lower-hybrid waves. We perform three 2D simulations with different box lengths along the shock front. The shock front oscillations are aperiodically damped in the smallest box with the fastest variation of the ion density, strongly damped in the intermediate one, and weakly damped in the largest box. The shock front oscillations perturb the magnetic field in a spatial interval that extends by several electron skin depths upstream and downstream of the shock front and could give rise to Whistler waves that propagate along the shock's magnetic field overshoot. Similar waves were observed in hybrid and PIC simulations and by the MMS satellite mission.

show abstract

Properties of lower hybrid waves

Cited by 6 publications

References 8 publications

Hybrid electrostatic waves in linearized gravity

Hybrid electrostatic waves in linearized gravity

Nonlinear lower hybrid wave equations in collisional tokamak plasmas

PIC simulations of stable surface waves on a subcritical fast magnetosonic shock front

Contact Info

Product

Resources

About