摘要:

AbstractJumps and hysteresis in discharge current are produced in a low‐pressure (10−5– 10−4Torr). magnetic field free, thermionic argon plasma discharge by varying discharge voltage, neutral pressure, or filament temperature. This behavior can be attributed to a region of negative differential resistance in the voltage versus current characteristic of the discharge. A model is presented in order to understand the physical processes leading to this negative res

ISSN:0005-8025    

DOI:10.1002/ctpp.19860260102

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractExperimental observations on the behavior of low‐pressure, thermionic argon discharges in magnetic cusp and mirror configurations are presented.I–Bcharacteristics showing jump and hysteresis behavior were found. In some cases, the sudden sharp decreases in discharge current that were observed were preceded by the onset of coherent, low‐frequency plasma oscillations, suggesting the possible role of instabil

ISSN:0005-8025    

DOI:10.1002/ctpp.19860260103

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0005-8025    

DOI:10.1002/ctpp.19860260104

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractElastic scattering of electrons by cut‐off Coulomb potentialUc(r) is investigated, whereUc(r) = 0, forr>rcandUc(r) = −1/r+ 1/rcforr≦rc. This is first considered in terms of classical, and later quantum mechanical (partial wave) methods in the low energy range 0 ≦ ϵ ≲ 1/rc, where ϵ is the energy of the free electron. Scattering in this energy region displays a number of particular characteristics, such as back scattering, at certain energies. It can be concluded that some agreement does exist between the classical and quantum mechani

ISSN:0005-8025    

DOI:10.1002/ctpp.19860260105

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThis work is devoted to the investigation of physical processes in a non‐equilibrium plasma of a binary mixture of inert gases. The degree of radial separation of the mixture was found to increase with increasing pressure of buffer gas and discharge current and to decrease with growing partial pressure of the admixture. The correlation of the radial and axial types of separation was shown experimentally. The kinetics of population of the metastable states He(23S) and Xe(3P22) and of charged particles was investigated using an impulse regime. The time for the establishment of the stationary state of the radial distribution of the components was found to be several times less than the time of reestablishment of the homogeneous distribution of the atomic component after switching off the discharge impulse. The phenomenon of a decreasing effective diffusion length of the discharge was found. This effect has essential influence on the time for the establishment of the stationary state of radial cataphoresi

ISSN:0005-8025    

DOI:10.1002/ctpp.19860260106

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe spectroscopic diagnostics has been carried out as an example for an argon plasma from Maecker‐Shumaker type electric arc supplied by periodic variable current. It is shown that the time‐dependent runs of intensity of the plasma light may be determined using an ordinary oscilloscope. We have stated that the electron concentrationNein the plasma is the most sensitive quantity to the current pulsations. In the percentage,Nevariations at the arc axis are approximately the same as the current o

ISSN:0005-8025    

DOI:10.1002/ctpp.19860260107

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractA common explanation is given for ion transport and strong broadband density fluctuations in tokamaks as a result of large anomalous electron transport near dominant magnetic surfaces (resp. in small magnetic islands). The main mechanism is local density flattening connected with an anomalous electron transport induced instationary radial electric field, which forces the ions via polarization drift to follow the electrons. For the density flattening process an exact solution of the time‐dependent diffusion equation for a linear initial profile over the island width is used. From this we also derive an expression for a temporal growing radial electric field. This positive field reaches its maximum at the density plateau. Strong viscous diffusion or instability‐induced transport between high and low electric field regions may now reverse the density flattening. Therefore relaxation oscillations result which may also explain the observed strong density and potential fluctuations in tokamaks. Several details of recent measurements of impurity ion behaviour and density fluctuations in tokamaks may be better explained with the theory given h

ISSN:0005-8025    

DOI:10.1002/ctpp.19860260108

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0005-8025    

DOI:10.1002/ctpp.19860260101

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY