摘要:

The imploding large Larmor radius Z pinch is studied numerically using a modified Vlasov-Fluid model including the effect of electron temperature. Sheared axial ion flow is seen to develop in agreement with the cold electron case with the flow profiles being of similar form and magnitude. These results contrasts with the equivalent fluid case where no flow would be generated. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374877

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The radial magnetic field profile during implosion of a reversed field current sheath in a theta-pinch was investigated through local measurements and simulation of hybrid code. The actual profile was defined by Hermite interpolation polynomial through mean value of the field at discrete radial position of measurements. Simulation profile was provided by the numerical code with appropriate initial conditions. Classical and anomalous collision process were taken in account in the theoretical model. The results indicated that anomalous effects play major role during the implosion phase of current sheath in a slow rising theta pinch device. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374878

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

In this work we report measurements of the electronic density and electronic temperature in a pulsed plasma system by using a double probe. We have implemented an automatic system of measure that start from the bias of a double electrostatic probe, allows us to register the complete curves of current-voltage in times of order of 10 ms; The electron density and electronic temperature can be extracted from the current-voltage I(V) characteristic. The advantage of this technique is that it allows us to get “in situ” quantity of information that when comparing them with the theoretical results using numeric methods for its simulation, provide us the necessary fits to quantify these parameters. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374879

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We present experimental observations of ionization waves in pulsed hollow cathode capillary discharges. When the capillary shield is at the anode potential, an anode directed ionization wave, with characteristic speed∼107&hthinsp;m/s,is observed. When the capillary shield is at the cathode potential, a cathode directed slower ionization wave, with characteristic speed∼104&hthinsp;m/s,is observed. The several orders of magnitude difference in the ionization wave speed can be attributed to the different initial electric field configuration in both polarities. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374880

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

A planar one-dimensional particle-in-cell simulation with Monte Carlo Collision (XPDP1) has been used to study 13.56 MHz mercury/argon discharge including metastable species for mercury and argon. It was used 1 Torr for argon and 0.05 Torr for mercury. Reaction such as argon metastable quenching by mercury atoms is taken into account for the mixture. It was found that this reaction is important in determining the metastable profiles for this mixture. The electron energy distribution function is plotted for mixture and for mercury at 0.05 Torr. It is slightly convex for the mixture, typical for high pressure discharge and concave for pure low pressure mercury plasma. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374881

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

A planar one-dimensional particle-in-cell simulation with Monte Carlo Collisions (XPDP1) has been used to study 13.56 MHz mercury discharge including metastable species. Reactions such as metastable creation, ionization from the metastable state, collisions between two metastables were taken into account. The effect of pressure and applied voltage on the metastable density was examined. At high pressure and high voltage the metastable profile is strongly peaked at the sheath edges. At low pressure and low voltage the density profiles are rather flat at the bulk plasma. The shape of the profile is determined by mean free path for electrons and metastables in the discharge. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374882

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The ionization growth inside the Hollow Cathode Region (HCR) of a Transient Hollow Cathode Discharge (THCD) under enhanced field due to the close proximity of the virtual anode has been studied using a statistical representation, with two cathode apertures, for different time interval sequences of identified events before breakdown. Statistical time distributions of experimental data set are analyzed to understand the mechanisms involved in the final stage, just before final electric breakdown. It has found a temporal sequence of the occurrence the different ionization events that describe this stage at pressure between 100 mTorr and 400 mTorr in hydrogen. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374883

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We investigate the effect of compressibility and magnetic field shear on the Kelvin‐Helmholtz instability in compressible stratified plasmas. We obtain two main results. First, for sufficiently low velocities the compressibility stabilizes the unstable modes present in an incompressible model (called main modes). This represents an important difference with the case without magnetic field shear. Second, new unstable modes appear (called secondary) which owe their existence to compressive perturbations. The secondary modes (of compressive character) determine the stability for values of velocity of the unperturbed flow that correspond to stable primary modes. In these cases the compressive modes do not disappear and may have appreciable growth rates. Therefore, compressibility effects may be relevant when discussing the stability of problems with magnetic field shear. Diagrams of stability and growth rates are shown that allow an easy visualization of the stability properties of a configuration

ISSN:0094-243X    

DOI:10.1063/1.3682831

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

This work presents measurements of temperature and density of a plasma as function of pressure. The plasma was produced by a pulsed discharge used to obtain TiN coatings. The system is composed by a chamber, which is filled with nitrogen at pressures that vary between 0.2 to 3.0 mb. Optical emission spectra were taken in different regions, and then, twenty lines were used to calculate the temperature using the relation line ‐line method. Moreover, the method of relation between lines of same species and consecutive ionization state is utilized to calculate the density of the plasma.

ISSN:0094-243X    

DOI:10.1063/1.3682832

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The ion kinetic energy spectrum in a pulsed vacuum arc is presented. The arc current lasts for 35 ms (HAFW), having a peak value of 500 A. A retarding field analyzer system, (consisting in an aperture plate, a charge selecting grid and an energy analyzer collector electrode) and Langmuir probes are employed. The plasma density inside the retarding field analyzer is obtained, and it is shown that the spatial charge between the grid‐collector region has some influence on the low energy part of the ion spectrum.

ISSN:0094-243X    

DOI:10.1063/1.3682833

出版商:AIP    

年代:1901

数据来源: AIP