A 3-D code has been designed to reconstruct the three-dimensional conductivity distribution in beds surrounding a wellbore from electromagnetic field data measured on the well axis. An arbitrarily oriented point magnetic dipole located on the well axis is considered as a source of electromagnetic radiation, where the well is parallel or normal to bed boundaries. In the specific case the solution to the vector Helmholtz equation for layered medium including the well and invasion zones is used to determine the background field E0. The order/size of the finite-difference operator of Helmholtz equation for the secondary field E, which arises from the 3D properties of the geological medium that differ from the background medium, is reduced by the thinning method. Formal application of the method produces a set of equations that connect the measured secondary field values on the axis with the unknown conductivity model. A biconjugate gradient method and simple iterative updates on the conductivity model are used to find the solution to the thinned system of equations, where the solution to the equations for the conductivity perturbation is sought by traditional regularization functional minimization. Specific examples are presented, which illustrate the possibilities of the method. It is shown that the use of the thinning method allows for a significant reduction in computational expenditure, without appreciable loss in the quality of the conductivity reconstruction.
The superlight source is the source moving with the superlight velocity. In particular, the electron current pulse propagating along some plane surface with vph > c is such a source. It is proposed to use the superlight source for high power microwave generation. The properties of the superlight source are investigated theoretically. It is shown that radiated microwave pulse is broadband and directed, may have the pulse duration approximately 10-12 sec and pulse power > 109 W.
A possibility to use the microwave superlight source for an electromagnetic wave focusing, a conceptual sketch and expected parameters of compact, charge particle accelerator with accelerating gradient of order of 10 Gev per meter and more on the basis of such device are considered. Investigation results of electromagnetic field space-time distribution near the focus and the process of charged particle acceleration are presented.
For generation of high power supershort directed electromagnetic pulse it is proposed to use faster-than-light electron current that is produced by the obliquely incident ionizing radiation illuminating plane metallic surface. The characteristic property of such source is the equality of the ionizing radiation incidence angle to the electromagnetic pulse emission angle. This fact allows to use the ordinary focusing optics methods for directed pulse generation. In the case of space-charge limited current the dominant wavelength of the electromagnetic pulse decreases with the intensity raise of ionizing radiation that leads to decrease of the electromagnetic radiation angular spread. For sufficiently high ionizing radiation intensity generation of directed, slowly spreading, beamlike electromagnetic pulse may be possible. By applying this principle of generation the limitation on accumulated energy area that is common to traditional technologies can be removed. Accordingly the power of microwave device may be increased by ten up to thousand times in comparison with existing sources, the duration of electromagnetic pulse may be reduced to tens nanoseconds or less and the spread of EMR beams may be realized less then 10-2. The increasing of produced radiation can be obtained by simple increasing emitted surface. In relation to this fact large-scale device with large radiated energy may be based on small 'elementary' sources just as house built from bricks. A compact form a small weight are the characteristic properties of microwave device with superlight electron current.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.