摘要:

Allowing for realistic magnetic field and plasma density profiles, a radial eigenvalue computer code was used to investigate flute modes in the ELMO Bumpy Torus (EBT).

ISSN:0031-9171    

DOI:10.1063/1.864255

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

One‐dimensional steady‐state radial profiles of a classical Z pinch are calculated. The effects of ion thermal conduction and bremsstrahlung radiation losses are included self‐consistently, as are Ohmic heating, pressure balance, and an equation of state. It is shown that the upper current limit of approximately 1.4 MA for an equilibrium pinch found when only bremsstrahlung losses are allowed is virtually unaffected by the inclusion of ion thermal conduction. However, solutions with lower currents are now allowed. The profile‐smoothing effect of ion thermal conduction is not sufficient to produce a pressure profile stable tom=0 modes. Total losses due to radial conduction are shown to be small for a thermonuclear plasma.

ISSN:0031-9171    

DOI:10.1063/1.864256

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

It is pointed out that velocity‐space anisotropy of a relativistic electron ring is reflected in the angular distribution of the intensity and polarization of the synchrotron emission, and it is suggested that this effect may be useful for direct measurement of the anisotropy. Results of sample computations for a loss‐cone type of distribution are presented.

ISSN:0031-9171    

DOI:10.1063/1.864257

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The quasilinear theory for the saturation of nonlinear tearing modes is modified to include rf driven currents. It is shown that the presence of lower hybrid driven currents can strongly suppress the growth of magnetic islands.

ISSN:0031-9171    

DOI:10.1063/1.864258

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A study is made of the slowing down of self‐consistent, large‐orbit ion rings due to small‐angle Coulomb scattering in a dense, low‐temperature plasma. A kinetic equation is derived for the ion‐ring distribution functionf(P,I,t), wherePis the canonical angular momentum, andIis an adiabatic invariant which is an implicit function ofPand the particle energy. The ratio of the time scale for the perpendicular momentum change (diffusion) to that for the parallel momentum change (drag) ism/M, withMthe ion mass andmthe electron mass. Therefore, drag is the dominant collisional effect, and the slowing down corresponds to incompressible flow in the (P,I) plane. This flow is calculated numerically by computing sequences of equilibria. Initially well‐trapped distribution functions are found to have essentially no particle loss during the first slowing‐down time &tgr;, which is defined as the time it would take a single ring particle to slow down to zero energy. In most of the cases studied, the rings shrink in both radius and in axial length, with the field reversal increasing by &bartil;10% within one &tgr;. The rate of loss of toroidal kinetic energy exceeds the loss of poloidal energy by a factor of typically 1.5–2.0. The self‐consistent toroidal electric field opposes the slowing down, increasing the ring life time by 20%–50% over the single‐particle slowing‐down time.

ISSN:0031-9171    

DOI:10.1063/1.864259

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The zero‐frequency cyclotron wave is studied on an unneutralized, magnetized relativistic‐electron beam. This stationary mode occurs where the Doppler‐shifted beam‐cyclotron dispersion branch crosses the wavenumber axis. In this experiment zero‐frequency‐cyclotron waves have been generated by the injection of foil (and foilless) diode beams into a drift tube. A linear‐cyclotron wave‐dispersion theory is presented which includes the radial electron‐energy variation &ggr;(r) due to beam space charge. The &ggr;(r) variation causes only one propagating eigenmode to exist for each azimuthal‐mode number. Numerical simulations of the beam and the cyclotron wave are described. Experimental measurements of the mode radial dependence, the wavelength scaling with magnetic field, and the wavelength scaling with beam energy are also presented.

ISSN:0031-9171    

DOI:10.1063/1.864260

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A nonlinear theory of a driven, inhomogeneous, one‐dimensional plasma of arbitrary temperature is presented. The model is solved numerically and analytically and detailed expressions are given for the saturated electric field excited at critical density. The results of the calculation are valid for arbitrary temperature and connect in a continuous manner the limits of cold wavebreaking and linear convective saturation. Comparison of the results of the calculation with particle simulations is made and good agreement is obtained.

ISSN:0031-9171    

DOI:10.1063/1.864261

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

An experimental study of the two‐plasmon decay instability is reported. An intense CO2laser (10.6 &mgr;m) was used to generate the instability in a long scale length, preformed plasma. The principal experimental diagnostic measurement was time‐resolved Thomson scattering, with resolution in either &ohgr; orkspace. The results show that the instability evolves basically in agreement with linear theories, then saturates by the nonlinear process of mode coupling to short‐wavelength ion fluctuations. At saturation, density fluctuations close to 20% are observed in both the electron and ion waves.

ISSN:0031-9171    

DOI:10.1063/1.864262

出版商:AIP    

年代:1983

数据来源: AIP

ISSN:0031-9171    

DOI:10.1063/1.864474

出版商:AIP    

年代:1983

数据来源: AIP