The measurement of ion acoustic turbulence and reduced thermal conductivity caused by a large temperature gradient in a laser heated plasma

Gray, Daniel; Kilkenny, J. D.

doi:10.1088/0032-1028/22/2/001

Cited by 156 publications

(53 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The total loss through a loop with footpoint area A is then L tot cond = A × L cond erg s −1 . However, for sufficiently large temperature gradients, such as occur in solar flares, the heat flux is expected to saturate, where two regimes of flux saturation can be defined (Gray & Kilkenny 1980). Battaglia et al (2009) showed that for typical flare densities and temperatures, including the conditions in the flare presented here, a regime is reached where the conductive heat flux is locally limited.…”

Section: Energy Budgetmentioning

confidence: 81%

Where Is the Chromospheric Response to Conductive Energy Input From a Hot Pre-Flare Coronal Loop?

Battaglia

Fletcher

Simões

2014

ApJ

View full text Add to dashboard Cite

Before the onset of a flare is observed in hard X-rays there is often a prolonged pre-flare or pre-heating phase with no detectable hard X-ray emission but pronounced soft X-ray emission suggesting that energy is being released and deposited into the corona and chromosphere already at this stage. This work analyses the temporal evolution of coronal source heating and the chromospheric response during this pre-heating phase to investigate the origin and nature of early energy release and transport during a solar flare. Simultaneous X-ray, EUV, and microwave observations of a well observed flare with a prolonged pre-heating phase are analysed to study the time evolution of the thermal emission and to determine the onset of particle acceleration. During the 20 minutes duration of the pre-heating phase we find no hint of accelerated electrons, neither in hard X-rays nor in microwave emission. However, the total energy budget during the pre-heating phase suggests that energy must be supplied to the flaring loop to sustain the observed temperature and emission measure. Under the assumption of this energy being transported toward the chromosphere via thermal conduction, significant energy deposition at the chromosphere is expected. However, no detectable increase of the emission in the AIA wavelength channels sensitive to chromospheric temperatures is observed. The observations suggest energy release and deposition in the flaring loop before the onset of particle acceleration, yet a model in which energy is conducted to the chromosphere and subsequent heating of the chromosphere is not supported by the observations.

show abstract

Section: Energy Budgetmentioning

confidence: 81%

Where Is the Chromospheric Response to Conductive Energy Input From a Hot Pre-Flare Coronal Loop?

Battaglia

Fletcher

Simões

2014

ApJ

View full text Add to dashboard Cite

show abstract

“…This is often done to treat nonlocal transport in plasmas with low collisionality, in which particle and energy fluxes at a given location are affected by conditions in distant regions of the plasma, which represents an important and complex problem. Often, ad hoc schemes are used in which the flux is simply limited to a fraction of its free-streaming value [1,8,13,[52][53][54]. Data such as presented here can provide a measurement of fluxes and thermodynamic gradients with high temporal and spatial resolution.…”

Section: Discussionmentioning

confidence: 99%

“…For collisional systems in which the mean free path is very small, particles remain close to local thermal equilibrium, and transport and collective motions can be described with a hydrodynamic treatment. Because of the increasing mean free path with particle kinetic energy, the situation can already change for mean free path on the order of or longer than 1% of the length scale of plasma gradients [1]. This gives rise to kinetic effects such as streaming plasmas and non-local transport, which are intensely studied because of their importance in many plasma environments, such as high-density laser-produced plasmas [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and astrophysical plasmas like the solar wind [19], solar atmosphere [20,21], solar flares [22], and supernovae [23].…”

Section: Introductionmentioning

confidence: 99%

Emergence of kinetic behavior in streaming ultracold neutral plasmas

et al. 2015

View full text Add to dashboard Cite

We create streaming ultracold neutral plasmas by tailoring the photoionizing laser beam that creates the plasma. By varying the electron temperature, we control the relative velocity of the streaming populations, and, in conjunction with variation of the plasma density, this controls the ion collisionality of the colliding streams. Laser-induced fluorescence is used to map the spatially resolved density and velocity distribution function for the ions. We identify the lack of local thermal equilibrium and distinct populations of interpenetrating, counter-streaming ions as signatures of kinetic behavior. Experimental data is compared with results from a one-dimensional, two-fluid numerical simulation.

show abstract

“…The limits of applicability of linear transport theory have been discussed by numerous authors [36][37][38]. For a relativistic plasma, it is required that the thermal-averaged momentum,…”

Section: Limits Of Validitymentioning

confidence: 99%

Transport coefficients of a relativistic plasma

Pike

Rose

2016

Phys. Rev. E

View full text Add to dashboard Cite

In this work, a self-consistent transport theory for a relativistic plasma is developed.Using the notation of Braginskii [S. I. Braginskii, in Reviews of Plasma Physics, ed. M. A. Leontovich (1965), Vol. 1, p.174], we provide semi-analytical forms of the electrical resistivity, thermoelectric and thermal conductivity tensors for a Lorentzian plasma in a magnetic field.This treatment is then generalized to plasmas with arbitrary atomic number by numerically solving the linearized Boltzmann equation. The corresponding transport coefficients are fitted by rational functions in order to make them suitable for use in radiation-hydrodynamic simulations and transport calculations. Within the confines of linear transport theory and on the assumption that the plasma is optically thin, our results are valid for temperatures up to a few MeV. By contrast, classical transport theory begins to incur significant errors above k B T ∼ 10 keV, e.g., the parallel thermal conductivity is suppressed by 15% at k B T = 20 keV due to relativistic effects.

show abstract

The measurement of ion acoustic turbulence and reduced thermal conductivity caused by a large temperature gradient in a laser heated plasma

Cited by 156 publications

References 24 publications

Where Is the Chromospheric Response to Conductive Energy Input From a Hot Pre-Flare Coronal Loop?

Where Is the Chromospheric Response to Conductive Energy Input From a Hot Pre-Flare Coronal Loop?

Emergence of kinetic behavior in streaming ultracold neutral plasmas

Transport coefficients of a relativistic plasma

Contact Info

Product

Resources

About