When a hot cluster expands, a transient matching between the plasma frequency and the laser frequency has been predicted, observed, and analyzed recently. The associate energy transfer to the electrons has been described as an enhanced collisional absorption. However, for hot plasmas the collision frequency is small and a collisionless resonant heating is more efficient. We set up and solve the problem of resonant collisional and collisionless cluster heating taking into account cluster expansion, laser pulse duration and pulse chirping. Moreover, we identify an efficient autoresonant mechanism of collisionless heating with a chirped laser pulse when the crossing between the plasmon frequency and the laser frequency is degenerate and the time derivatives of these two frequencies are equal at the crossing time. Transition between collisional regime of cluster heating and collisionless one is discussed.
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http://dx.doi.org/10.1103/PhysRevE.67.066405 | DOI Listing |
Nat Astron
January 2024
Physics Department, University of Otago, Dunedin, New Zealand.
The dissipation of turbulence in astrophysical systems is fundamental to energy transfer and heating in environments ranging from the solar wind and corona to accretion disks and the intracluster medium. Although turbulent dissipation is relatively well understood in fluid dynamics, astrophysical plasmas often exhibit exotic behaviour, arising from the lack of interparticle collisions, which complicates turbulent dissipation and heating in these systems. Recent observations by NASA's Parker Solar Probe mission in the inner heliosphere have shed new light on the role of ion cyclotron resonance as a potential candidate for turbulent dissipation and plasma heating.
View Article and Find Full Text PDFSci Rep
January 2023
Faculty of Sciences, Department of Physics, Azarbaijan Shahid Madani University, 51745-406, Tabriz, Iran.
Based on the effective Schrödinger-Poisson model a new physical mechanism for resonant hot-electron generation at irradiated half-space metal-vacuum interface of electron gas with arbitrary degree of degeneracy is proposed. The energy dispersion of undamped plasmons in the coupled Hermitian Schrödinger-Poisson system reveals an exceptional point coinciding the minimum energy of plasmon conduction band. Existence of such exceptional behavior is a well-know character of damped oscillation which in this case refers to resonant wave-particle interactions analogous to the collisionless Landau damping effect.
View Article and Find Full Text PDFNat Commun
October 2022
Southwest Research Institute, San Antonio, TX, USA.
Electromagnetic whistler-mode waves in space plasmas play critical roles in collisionless energy transfer between the electrons and the electromagnetic field. Although resonant interactions have been considered as the likely generation process of the waves, observational identification has been extremely difficult due to the short time scale of resonant electron dynamics. Here we show strong nongyrotropy, which rotate with the wave, of cyclotron resonant electrons as direct evidence for the locally ongoing secular energy transfer from the resonant electrons to the whistler-mode waves using ultra-high temporal resolution data obtained by NASA's Magnetospheric Multiscale (MMS) mission in the magnetosheath.
View Article and Find Full Text PDFPhys Rev Lett
October 2022
Department of Physics, The Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom.
The dissipation of magnetized turbulence is an important paradigm for describing heating and energy transfer in astrophysical environments such as the solar corona and wind; however, the specific collisionless processes behind dissipation and heating remain relatively unconstrained by measurements. Remote sensing observations have suggested the presence of strong temperature anisotropy in the solar corona consistent with cyclotron resonant heating. In the solar wind, in situ magnetic field measurements reveal the presence of cyclotron waves, while measured ion velocity distribution functions have hinted at the active presence of cyclotron resonance.
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July 2022
Institute for Plasma Research, Bhat, Gandhinagar, 382 428, India.
In the few-cycle pulse regime of laser-cluster interaction (intensity [Formula: see text], wavelength [Formula: see text] nm), laser absorption is mostly collisionless and may happen via anharmonic resonance (AHR) process in the overdense (cluster) plasma potential. Many experiments, theory and simulation show average absorbed energy per cluster-electron ([Formula: see text]) close to the electron's ponderomotive energy ([Formula: see text]) in the collisionless regime. In this work, by simple rigid sphere model (RSM) and detailed particle-in-cell (PIC) simulation, we show enhanced [Formula: see text] 30-70[Formula: see text]-a 15-30 fold increase-with an external (crossed) magnetic field near the electron-cyclotron resonance (ECR).
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