摘要:

Echoes associated with the bounce motion of ions are observed in a mirror fusion device. The echoes are initiated by means of two sucessive perturbations of the confining magnetic field. The characteristic time for echo cancellation under diffusion in velocity space is measured. This time is somewhat less than the predicted classical time for Coulomb collisions. The discrepancy may be accounted for either by rf turbulent fields at &ohgr;cior by impurities both of which provide an enhancement of the diffusion coefficient.

ISSN:0031-9171    

DOI:10.1063/1.861702

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Measurements of cross‐field diffusion were made in the levitated octupole using two independent methods. First, the magnitude and scaling ofD⊥with density,n, and field strength,B, were determined by direct measurements of the particle flux onto an internal ring surface. Second, the shape of the density profile and the time decay of the density at the separatrix were compared with solutions of a diffusion equation model. Both methods indicated thatD⊥was proportional ton−1/2and independent ofB. The plasma was created by gun injection into the purely poloidal magnetic field and the initial parameters werene∼5 ×109cm−3,Ti∼20 eV,Te∼5 eV. The observed diffusion scaling can be understood within the framework of vortex diffusion in a high‐dielectric constant plasma if the spectrum of waves is enhanced in energy over thermal levels with an effective temperature,T*, of 104eV.

ISSN:0031-9171    

DOI:10.1063/1.861703

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The transition between the anomalous diffusion previously reported in pulsed multipoles and classical diffusion has been observed at low poloidal magnetic fields,B≲100 G. The helium plasma parameters werene=1010–1011cm−3,Ti∼Te∼0.2 eV. The anomalous diffusion seen at higher magnetic fields scaled like vortex diffusion, but the transition point corresponds to a nonthermal vortex spectrum with effective temperature,T*∼106eV. Transition from anomalous to classical regime is observed on a classical viscous damping time scale.

ISSN:0031-9171    

DOI:10.1063/1.861704

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The curvature effects on unsteady free convection during the initial period of a suddenly heated circular cylinder immersed in a viscous liquid are studied. It is shown that the curvature leads to an increase in skin friction as well as heat transfer rate from the surface of the cylinder.

ISSN:0031-9171    

DOI:10.1063/1.861705

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The final stage of one plate falling onto another, with a fluid in between, is found to be highly viscous. The mean height decays ast−1/2. For an elliptic plate, perturbation of the inclination decays ast−&bgr;/2, where 2⩽&bgr;⩽5. Thus, floating always occurs. PFLDA/JAN 7

ISSN:0031-9171    

DOI:10.1063/1.861706

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Jets of Newtonian liquid issuing from circular tubes at high Reynolds number are known to contract. The effect of the length of the tube or position of a constriction in the tube, upon the asymptotic contraction ratio is investigated.

ISSN:0031-9171    

DOI:10.1063/1.861687

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The commonly employed results of Silin for inverse bremsstrahlung with strong field corrections are obtained in a simple manner from a Lorentz collision operator. The effective collision frequencies for linearly and circularly polarized light are given for arbitrary pump strength.

ISSN:0031-9171    

DOI:10.1063/1.861688

出版商:AIP    

年代:1977

数据来源: AIP