摘要:

The theory of the Raman sidescattering instability in an inhomogeneous plasma is revisited. The growth rate is found from the eigenvalue of a second‐order ordinary differential equation in the Fourier domain. Under certain, rather easily satisfied constraints, the normalized growth rate depends on a single parameter involving laser strength, gradient scale length, and resonant density.

ISSN:0031-9171    

DOI:10.1063/1.865341

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

In 0.26 &mgr;m wavelength laser experiments that were performed in planar geometry with irradiances between 1013and 1015W/cm2, the ablation pressure and the target velocity have been measured using a shock‐velocity measurement and the double foil technique, respectively. The conditions are discussed that must be satisfied if the double‐foil technique is to give an accurate measurement of the velocity of the dense part of the target. The rocket model has also been improved using a time‐dependent applied pressure pulse, in order to accurately describe the relation between ablation pressure, target velocity, and ablated fraction. Pressures up to 50 Mbar have been easily generated since lateral energy transport is rather low with a 0.26 &mgr;m wavelength laser.

ISSN:0031-9171    

DOI:10.1063/1.865342

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A theoretical lower limit to the magnetic field strength required for critical ionization velocity (vc) interaction is found to correspond to the requirementv<vA(1+&bgr;e)1/2, which can also be expressed as &ohgr;pe/&ohgr;ce<(c/v)[(1+&bgr;e) ×me/mi]1/2. This limit is found to agree, within the experimental uncertainties, with the results from all thevcexperiments in the impact configuration. The different experiments have very different physical characteristics, and cover large ranges in plasma densities, stream velocities, and magnetic field strengths. A theoretical upper limit to the magnetic field strength is also found, corresponding to the requirement &ohgr;pe/&ohgr;ce≫(me/mn)1/2.

ISSN:0031-9171    

DOI:10.1063/1.865343

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Field‐reversed configuration translation into a conducting cylinder that does not conserve flux is analyzed and compared to translation into a flux conserver. The differences are found to be important for the design of an adiabatic compressional heating experiment.

ISSN:0031-9171    

DOI:10.1063/1.865419

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

In the Tokapole II tokamak [Nucl. Fusion19, 1509 (1979)] the three‐dimensional structure of the rapid sawtooth crash that accompanies internal disruptions has been observed. The sawtooth crash is helical, i.e., the decrease in soft x‐ray intensity occurs along aq=1 helical contour, in accord with the standard reconnection model. The poloidally asymmetric radial expansion of the crash inward from theq=1 surface provides a measure of the reconnection time consistent with single helicity reconnection from a growing, nonrotating magnetic island.

ISSN:0031-9171    

DOI:10.1063/1.865344

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

In a recent paper, Vanden‐Broeck computed the shape of a two‐dimensional jet emerging from a vertical nozzle [Phys. Fluids27, 1090 (1984)]. He showed that the slope of the free surface at the separation points is either horizontal or vertical. Here the local behavior of the flow in the neighborhood of the separation point is investigated. It is shown that an additional solution with a 120 degree angle is also possible.

ISSN:0031-9171    

DOI:10.1063/1.865345

出版商:AIP    

年代:1985

数据来源: AIP