scholarly journals Raman Processes in the Helium Atom in Intense Fields

1975 ◽  
Vol 28 (1) ◽  
pp. 35
Author(s):  
RK Thareja ◽  
Man Mohan ◽  
V Nayak ◽  
SN Haque
Keyword(s):  
Helium Atom ◽  
General Expression ◽  
High Intensity ◽  
Transition Amplitude ◽  
Higher Order ◽  
Nonlinear Behaviour ◽  
S Wave ◽  
Intensity Parameter ◽  
Intense Fields ◽  
Hydrogenic Model

Using the hydrogenic model for the helium atom, the amplitude of transition from states He(ls) to He(ls, nl) by absorption of N photons of an intense field together with the emission of one Raman photon is evaluated. From the general expression for the transition amplitude, the particular case of transition from He(ls) to He(ls, 2p) is considered. The 'reduced' transition amplitude is plotted against the number of photons N involved and against the intensity parameter y st;parately. It is found that the s wave contributes maximaly to the transition amplitude. An important feature of the calculations is the appearance of nonlinear behaviour at high intensity. The dominance of higher order processes over lower ones at high intensity is also found.

Higher-order Stark effect on an excited helium atom

1999 ◽  
Vol 60 (2) ◽  
pp. 986-995 ◽  
Author(s):  
A. Derevianko ◽  
W. R. Johnson ◽  
V. D. Ovsiannikov ◽  
V. G. Pal’chikov ◽  
D. R. Plante ◽  
...  
Keyword(s):  
Helium Atom ◽  
Stark Effect ◽  
Higher Order ◽  
Excited Helium

Higher-Order Stark Effect on Magnetic Fine Structure of the Helium Atom

2001 ◽  
pp. 753-761 ◽  
Author(s):  
Aleksandr Magunov ◽  
Vitaly Ovsiannikov ◽  
Vitaly Pal’chikov ◽  
Victor Pivovarov ◽  
Gebhard von Oppen
Keyword(s):  
Fine Structure ◽  
Helium Atom ◽  
Stark Effect ◽  
Higher Order

EXTRACTING SUB-SURFACE INFORMATION FROM LONG OFFSET P-WAVE DATA—A CHEAPER ALTERNATIVE TO MULTICOMPONENT OBC FOR EXPLORATION?

2002 ◽  
Vol 42 (1) ◽  
pp. 627
Author(s):  
R.G. Williams ◽  
G. Roberts ◽  
K. Hawkins
Keyword(s):  
Seismic Energy ◽  
Higher Order ◽  
P Wave ◽  
S Wave ◽  
Additional Information ◽  
Wave Data ◽  
Wave Velocities ◽  
Avo Inversion ◽  
Long Offset ◽  
Multicomponent Data

Seismic energy that has been mode converted from pwave to s-wave in the sub-surface may be recorded by multi-component surveys to obtain information about the elastic properties of the earth. Since the energy converted to s-wave is missing from the p-wave an alternative to recording OBC multi-component data is to examine p-wave data for the missing energy. Since pwave velocities are generally faster than s-wave velocities, then for a given reflection point the converted s-wave signal reaches the surface at a shorter offset than the equivalent p-wave information. Thus, it is necessary to record longer offsets for p-wave data than for multicomponent data in order to measure the same information.A non-linear, wide-angle (including post critical) AVO inversion has been developed that allows relative changes in p-wave velocities, s-wave velocities and density to be extracted from long offset p-wave data. To extract amplitudes at long offsets for this inversion it is necessary to image the data correctly, including correcting for higher order moveout and possibly anisotropy if it is present.The higher order moveout may itself be inverted to yield additional information about the anisotropy of the sub-surface.

scholarly journals Unusual Response of Thin LiTaO3 Films to Intense Microwave Pulses

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3588
Author(s):  
Haojia Chen ◽  
Qiong Gao ◽  
Baoliang Qian ◽  
Lishan Zhao
Keyword(s):  
Nonlinear Behaviour ◽  
Small Signal ◽  
Large Signal ◽  
Signal Model ◽  
Small Signal Model ◽  
Wide Range ◽  
Microwave Pulses ◽  
Intense Fields ◽  
Voltage Signal ◽  
Wave Sensors

Fundamentally different responses of a LiTaO 3 thin film detector are observed when it is subjected to short microwave pulses as the pulse intensity is altered over a wide range. We start from weak microwave pulses which lead to only trivial pyroelectric peak response. However, when the microwave pulses become intense, the normally expected pyroelectric signal seems to be suppressed and the sign of the voltage signal can even be completely changed. Analysis indicates that while the traditional pyroelectric model, which is a linear model and works fine for our data in the small regime, it does not work anymore in the large signal regime. Since the small-signal model is the key foundation of electromagnetic-wave sensors based on pyroelectric effects, such as pyroelectric infrared detecters, the observation in this work suggests that one should be cautious when using these devices in intense fields. In addition, the evolution of detector signal with respect to excitation strength suggests that the main polarisation process is changed in the large signal regime. This is of fundamental importance to the understanding on how crystalline solids interact with intense microwaves. Possible causes of the nonlinear behaviour is discussed.

Nonlinear behaviour of contained inertia waves

1996 ◽  
Vol 315 ◽  
pp. 151-173 ◽  
Author(s):  
Richard Manasseh
Keyword(s):  
Fundamental Mode ◽  
Experimental Studies ◽  
Higher Order ◽  
Time Dependent ◽  
Linear Wave ◽  
Wave System ◽  
Nonlinear Behaviour ◽  
Rotating Fluid ◽  
Weakly Nonlinear ◽  
Higher Order Modes

Rotating fluid-filled containers are systems which admit inertial oscillations, which at appropriate frequencies can be represented as inertia wave modes. When forced by a time-dependent perturbation, systems of contained inertia waves have been shown, in a number of experimental studies, to exhibit complex and varied breakdown phenomena. It is particularly hard to determine a forcing amplitude below which breakdowns do not occur but at which linear wave behaviour is still measurable. In this paper, experiments are presented where modes of higher order than the fundamental are forced. These modes exhibit more complex departures from linear inviscid behaviour than the fundamental mode. However, the experiments on higher-order modes show that instabilities begin at nodal planes. It is shown that even a weakly nonlinear contained inertia-wave system is one in which unexpectedly efficient interactions with higher-order modes can occur, leading to ubiquitous breakdowns. An experiment with the fundamental mode illustrates the system's preference for complex transitions to chaos.

scholarly journals An electron of helium atom under a high-intensity laser field

Laser Physics ◽  
2017 ◽  
Vol 27 (2) ◽  
pp. 026004 ◽  
Author(s):  
Babatunde James Falaye ◽  
Guo-Hua Sun ◽  
Adenike Grace Adepoju ◽  
Muhammed S Liman ◽  
K J Oyewumi ◽  
...  
Keyword(s):  
Helium Atom ◽  
High Intensity ◽  
Laser Field ◽  
High Intensity Laser ◽  
Intensity Laser

scholarly journals A CBF calculation of 1S0 Superfluidity in the Inner Crust of Neutron Stars

2019 ◽  
Vol 17 ◽  
pp. 23
Author(s):  
G. Pavlou ◽  
E. Mavrommatis ◽  
Ch. C. Moustakidis ◽  
J. W. Clark
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Basis Function ◽  
Correlation Functions ◽  
Short Range ◽  
Higher Order ◽  
Neutron Matter ◽  
S Wave ◽  
Short Range Correlations

Singlet S-wave superfluidity of dilute neutron matter in the inner crust of neutron stars is studied within the correlated BCS (Bardeen, Cooper, Schrieffer) method, taking into account both pairing and short-range correlations. First, the equation of state (EOS) of normal neutron matter is calculated within the correlated-basis-function (CBF) method in lowest cluster order using the Argonne V18 and V4′ potentials and Jastrow-type correlation functions. The 1S0 superfluid gap is then calculated with these potentials and correlation functions. The dependence of our results on the choice of the correlation functions is ana- lyzed and the role of higher-order cluster corrections is considered. The values obtained for the 1S0 gap within this simplified scheme are comparable to those from other, more elaborate, methods.

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