Observation of Energy Transfer between Frequency-Mismatched Laser Beams in a Large-Scale Plasma

1996 ◽  
Vol 76 (12) ◽  
pp. 2065-2068 ◽  
Author(s):  
R. K. Kirkwood ◽  
B. B. Afeyan ◽  
W. L. Kruer ◽  
B. J. MacGowan ◽  
J. D. Moody ◽  
...  
2005 ◽  
Vol 23 (10) ◽  
pp. 3365-3373 ◽  
Author(s):  
J. Birn ◽  
M. Hesse

Abstract. Magnetic reconnection is the crucial process in the release of magnetic energy previously stored in the magnetotail in association with substorms. However, energy transfer and dissipation in the vicinity of the reconnection site is only a minor part of the energy conversion. We discuss the energy release, transport, and conversion based on large-scale resistive MHD simulations of magnetotail dynamics and more localized full particle simulations of reconnection. We address in particular, where the energy is released, how it propagates and where and how it is converted from one form into another. We find that Joule (or ohmic) dissipation plays only a minor role in the overall energy transfer. Bulk kinetic energy, although locally significant in the outflow from the reconnection site, plays a more important role as mediator or catalyst in the transfer between magnetic and thermal energy. Generator regions with potential auroral consequences are located primarily off the equatorial plane in the boundary regions of the plasma sheet.


1977 ◽  
Vol 31 (4) ◽  
pp. 253-271 ◽  
Author(s):  
W. M. Tolles ◽  
J. W. Nibler ◽  
J. R. McDonald ◽  
A. B. Harvey

Coherent anti-Stokes Raman spectroscopy (CARS) is a relatively new kind of Raman spectroscopy which is based on a nonlinear conversion of two laser beams into a coherent, laser-like Raman beam of high intensity in the anti-Stokes region. The emission is often many orders of magnitude greater than normal Raman scattering and, because of the coherent and anti-Stokes character of radiation, the method is very useful for obtaining Raman spectra of fluorescing samples, gases in discharges, plasmas, combustion, atmospheric chemistry. In this paper we outline the basic theory behind CARS and describe its unusual effects and drawbacks. We review the research to date on various materials, and indicate the possible future direction, utility and applications of CARS such as surface studies, fluctuation phenomena, reaction dynamics, photochemistry, kinetics, relaxation, and energy transfer.


Laser Physics ◽  
2021 ◽  
Vol 31 (12) ◽  
pp. 125401
Author(s):  
Yaling Yang ◽  
Yanli Zhang ◽  
Junyong Zhang ◽  
You Li ◽  
Dean Liu

Abstract A Hartmann wavefront sensor is a type of wavefront detection instrument that has been widely used in various fields. Traditional Hartmann wavefront sensors usually comprise a monofocal refraction lenslet array to segment the wavefront at the entrance pupil. Each wavelet is focused at the focal plane along the projection of the lenslet, forming the foci array. Unlike the multifocal self-interference Taiji-lenslet array, a type of multifocal diffraction Taiji-lenslet array was proposed in this study to improve the measurement accuracy using the weighted centroid location algorithm of these multifocal spots, where the latter is more easily designed than the former. An optical experiment was implemented using the multifocal diffraction Taiji-lenslet array to verify its effectiveness. As a type of diffractive lens, a large-aperture Taiji-lenslet array can be easily fabricated via lithography, which has great potential for application in the measurement of large-scale laser beams and optical elements.


2006 ◽  
Vol 23 (10) ◽  
pp. 2113 ◽  
Author(s):  
Sarik R. Nersisyan ◽  
Nelson V. Tabiryan ◽  
C. Martin Stickley

1976 ◽  
Vol 73 ◽  
pp. 333-333
Author(s):  
A. P. Moses ◽  
R. C. Smith

The anomalous mass-luminosity relation for the components of a contact binary system is usually explained by postulating strong energy transfer from the primary to the secondary. It has been assumed that the transfer occurs in the common convective envelope surrounding the two stars, but so far the only attempt at a model for the energy transfer has been the sideways convection model of Hazlehurst and Meyer-Hofmeister (1973), which assumes a large-scale circulation of material between the two components.Any detailed discussion of the dynamics in the common envelope must take account of the predominantly vertical motions associated with normal thermal convection, of Coriolis forces and of viscosity. We have constructed an approximate model for the horizontal transfer of energy between the two components, using a mixing-length approach and taking all three factors into account. The major factors are the vertical convection and the Coriolis forces, which together prevent a large-scale circulation of the type proposed by Hazlehurst and Meyer-Hofmeister. Instead, the flow breaks up into smallscale eddies whose horizontal scale is determined by the interaction of convection, Coriolis forces and viscosity. This has the important qualitative consequence that horizontal energy transfer will occur only if the mean horizontal pressure gradient between the two stars exceeds a certain minimum value. This condition can easily be satisfied in the adiabatic zone of the envelope, but may be an important restriction in the super-adiabatic zone.Using our model, we were able to estimate the entropy difference between components which is required to transfer enough energy to explain the observed mass-luminosity relation. We found that equal entropy models are possible only if the contact is deep. Unequal entropy models are possible for any degree of contact, so long as the contact extends down as far as the adiabatic zone. If, as has been suggested, the depth of contact increases during evolution then zero-age models must have shallow contact and hence unequal entropies. Deep contact equal entropy models would then form as a result of evolution.A difficulty is that in our model insufficient energy transfer can occur in the super-adiabatic zone to produce WUMa light curves for the unequal entropy models. This may mean that further work is needed on the exact surface conditions in these stars.


2019 ◽  
Vol 26 (8) ◽  
pp. 082708 ◽  
Author(s):  
L. Yin ◽  
B. J. Albright ◽  
D. J. Stark ◽  
W. D. Nystrom ◽  
R. F. Bird ◽  
...  

2011 ◽  
Vol 18 (2) ◽  
pp. 023108
Author(s):  
Deepak Tripathi ◽  
R. Uma ◽  
V. K. Tripathi

Sign in / Sign up

Export Citation Format

Share Document