IPG Photonics

About: IPG Photonics is a based out in . It is known for research contribution in the topics: Laser & Fiber laser. The organization has 903 authors who have published 1241 publications receiving 63339 citations.

On the trees of quantum fields

Abstract: The solution of some equations involving functional derivatives is written as a series indexed by planar binary trees. The terms of the series are given by an explicit recursive formula. Some algebraic properties of these series are investigated. Several examples are treated in the case of quantum electrodynamics: the complete fermion and photon propagators, the two-body Green function and the one-body Green function in the presence of an external source, the complete vacuum polarization, the electron self-energy and the irreducible vertex.

A Three-Dimensional Simulation of Collisional-Interchange-Instability in the Equatorial-Low-Latitude Ionosphere

Abstract: We present a three-dimensional simulation of collisional-interchange-instability in the equatorial-low-latitude F region of ionosphere. The instability is responsible for the generation of large plasma density depletion or bubble. General 3D potential and continuity equations are derived to simulate the phenomena. To understand the linear aspect of the instability, the general 3D linear growth rate is derived using 3D potential equation. The linear growth characteristics are compared with earlier field-aligned-integrated growth analyses. The numerical simulation of bubble in the 3D spherical polar geometry is finally presented. Distinct evolution characteristics of bubble in 3D and 2D simulation are further discussed.

Water Circulations on La Soufriere Volcano Inferred by Self-Potential Surveys (Guadeloupe, Lesser Antilles). Renew of Volcanic Activity?

Abstract: Soufriere volcano is an andesite explosive volcano located in Guadeloupe in the lesser Antilles arc. Since the last magmatic eruption dated 1440 ± 40 AD several violent phreatic eruptions have occurred. The two last 1956 and 1976-1977 phreatic/phreato magmatic eruptions were preceded by several decades of quietness. During these quiet periods, hydrothermalization and argillization are expanding due to high tropical rainfalls (10 to 12 m per year). Sealing of fractures yields more and more difficult the release of thermal stresses developed by the magmatic body supposed to be at 6 km depth. Overpressures are increasing in confined superficial water tables. Renew of seismic activity started in May 1992. About 1400 earthquakes were recorded between May and December 1992. The onset of activity was preceded, one year before, by a slight increase of vapor emission inside South crater located on Soufriere dome at the upper end of August 30, 1976 fault, by the reactivation of the small Tarade hot spring dried up since the 1976-1977 eruption, and by the appearance of a new, low flow rate, hot spring called Pas du Roy (about 30°C). A Self Potential (S.P.) survey has been performed in July 1992 on Soufriere massif. The S.P. anomalies evidence structural heterogeneities and ground waters flowing within the massif. A large, smooth, positive S.P. anomaly, composed of two localized and pronounced anomalous zones, is spreading on the south-west-south-east sector of the dome basis. The larger anomalous zone is located on Morne Mitan in the axis of the regional Ty and August, 30, 1976 faults. This zone is extending along the contact zone between Soufriere dome and Carmichael cone. The 1992 survey is compared with 1987 survey. Soufriere dome is now submitted to a ring of positive S.P. anomalies which are lying along the inner part of Amic crater. The positive anomalous zone located on Morne Mitan has developed since 1987. The second anomalous zone, located on the south-west part of the dome, was not observed in 1987. The amplitude reaches 200 mV. The S.P. mapping points out that warm ground water beneath the south part of the volcano summit, along clayey beds, could generate the collapse of the south-west-south-east sector of Soufriere dome.

Using syntectonic remagnetizations for fold geometry and vertical axis rotation: the example of the Cévennes border (France)

Abstract: SUMMARY Classical progressive unfolding makes a distinction between pre-folding, post-folding or synfolding magnetization. It yields the direction of magnetization only in the two first cases. To determine the direction of synfolding magnetization, possible different unfolding percentages during remagnetization have to be assumed according to the site. The small circle approach of Surmont et al. not only leads to this direction, but also to the dip value at each site during ◦ )

Detecting Atmospheric Perturbations Produced by Venus Quakes

Abstract: [1] The possibility to detect seismic activity on Venus by using the mechanical coupling of the solid-atmosphere system is investigated. First, the atmospheric attenuation of infrasonic waves produced by quakes is theoretically determined from a pure CO2 atmospheric model, demonstrating that frequencies below 0.1 Hz are amplified by a factor of 10 000 above 120 km altitude. With a simple quake model, an upper limit of infrasonic adiabatic temperature and density perturbations above the source is estimated. Then, we demonstrate that the temperature increase due to high altitude acoustic energy dissipation above a quake is large enough to be measured by remote sensing methods. Finally, the expected post-seismic effects are analyzed in the framework of the VIRTIS instrument on board the ESA Venus Express mission.