摘要:

The interaction of CO2laser pulses of 25 nsec duration with solid targets for laser power densities up to 2×1012Wcm−2on target is described. Measurements were made of the plasma electron density, electron temperature, infrared plasma emission, and plasma blow‐off ion velocity. The results are discussed in terms of their implications for future compression experiments involving long‐pulse lasers.

ISSN:0031-9171    

DOI:10.1063/1.863315

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Some aspects of the self‐trapped propagation of beams of strong electromagnetic radiation are discussed. A comparison is made between a variational approach and the commonly used paraxial ray approximation, demonstrating how the latter gives an erroneous result for the nonlinear wavenumber.

ISSN:0031-9171    

DOI:10.1063/1.863316

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A free electron laser instability is investigated for a relativistic annular electron beam propagating through a helical wiggler magnetic field. It is assumed that the beam is thin, with radial thickness (2a) much smaller than the beam radius (R0), and that &ngr;/&ggr;b≪1, where &ngr; is Budker’s parameter. The stability analysis is carried out within the framework of the linearized Vlasov–Maxwell equations for perturbations with general azimuthal harmonic numberland radial mode numbers, including the important influence of (a) finite beam geometry in the radial direction, (b) positioning of the beam radius relative to the outer conducting wall (R0/Rc), and (c) finite wiggler amplitude (&dgr;B). All of these effects are shown to have an important influence on stability behavior. Moreover, the maximum coupling between the transverse and longitudinal modes increases substantially with increasing radial mode numbers. It is also found that the transverse magnetic (TM) mode has slightly larger growth rate than the transverse electric (TE) mode.

ISSN:0031-9171    

DOI:10.1063/1.863317

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Rapid heating of electrons and ions has been observed in a high‐voltage toroidal theta pinch with initial bias fields either parallel or antiparallel to the fast rising toroidal field. The elimination of rapid end losses has permitted higher electron temperatures to be attained. In contrast to the results of linear theta pinches in whichTe≲0.3Ti, it is now found thatTe∼Ti. The ion heating is similar to that observed in the linear case indicating that the effective microinstability heating process is maintained in a toroidal system. Higher temperatures were observed with antiparallel bias fields, but in both cases superthermal electron populations were observed indicating that the turbulent heating process involves electron tail formation.

ISSN:0031-9171    

DOI:10.1063/1.863318

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The viscous decay rate of a packet of gravity‐induced water waves in the form of an envelope soliton is twice the decay rate of the corresponding uniform train of infinitesimal waves.

ISSN:0031-9171    

DOI:10.1063/1.863319

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The resonant absorption of Alfve´n waves is investigated using a resistive magnetohydrodynamic fluid code. At very low frequencies, heating at the shear Alfve´n resonance is found to be inefficient.

ISSN:0031-9171    

DOI:10.1063/1.863320

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A hollow relativistic electron beam propagating in a cylindrical drift tube is subject to the diocotron instability. It is shown that if the beam is not azimuthally symmetric, then the diocotron effect can disrupt the beam in a substantially shorter time than in the symmetric case.

ISSN:0031-9171    

DOI:10.1063/1.863321

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A potential overshoot is made in a current‐carrying plasma with a longitudinal magnetic field by a floating disk probe which works as a disturber. The overshoot appears behind the disturber in the electron current. Its transverse and longitudinal scale lengths are measured and discussed.

ISSN:0031-9171    

DOI:10.1063/1.863322

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A comment on the adiabatic modifications to plasma turbulence theory is presented.

ISSN:0031-9171    

DOI:10.1063/1.863323

出版商:AIP    

年代:1981

数据来源: AIP