An Arc maintained on an Isolated Metal Plate exposed to a Plasma

Robson, A. E.; Thonemann, P. C.

doi:10.1088/0370-1328/73/3/317

Cited by 91 publications

(54 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A floating object assumes a negative floating potential relative to the plasma potential in order to balance the electrical current of the more mobile negative plasma electrons against the less mobile positive ions [59,60] …”

Section: Conventional and Unipolar Arcsmentioning

confidence: 99%

The evolution of ion charge states in cathodic vacuum arc plasmas: a review

Anders¹

2012

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

ACKNOWLEDGMENTMany of the here-collected results are based on ideas and contributions by close friends and colleagues. Running the risk of offending those not mentioned, I gratefully acknowledge the input over the years from just a few: B. Jüttner, E. Hantzsche, P. Siemroth, T. Schülke, I. Brown, E. Oks and G. Yushkov. This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. DISCLAIMERThis document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor The Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or The Regents of the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or The Regents of the University of California. 2The evolution of ion charge states in cathodic vacuum arc plasmas: a review André AndersLawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 53, Berkeley, California 94720, USA Email: aanders@lbl.gov AbstractCathodic vacuum arc plasmas are known to contain multiply charged ions. 20 years after "Pressure Ionization: its role in metal vapour vacuum arc plasmas and ion sources" appeared in vol. 1 of Plasma Sources Science and Technology, it is a great opportunity to re-visit the issue of pressure ionization, a non-ideal plasma effect, and put it in perspective to the many other factors that influence observable charge state distributions, such as the role of the cathode material, the path in the density-temperature phase diagram, the "noise" in vacuum arc plasma as described by a fractal model approach, the effects of external magnetic fields and charge exchange collisions with neutrals. A much more complex image of the vacuum arc plasma emerges putting decades of experimentation and modeling in perspective.

show abstract

Section: Conventional and Unipolar Arcsmentioning

confidence: 99%

The evolution of ion charge states in cathodic vacuum arc plasmas: a review

Anders¹

2012

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…It is interesting to note that the arcing corresponds to unipolar arcing, because the cover plate of the cathode was at the floating potential during the experiments. In unipolar arcing, the electric emission from the cathode spot is compensated by total current flow to the surface from the surrounding plasma and local current produced with arcing [14,15]. Although the outside of the molybdenum cover was not directly exposed to the helium plasma, the inside of the cover should be attached to the plasma.…”

Section: Initiation Of Unipolar Arcingmentioning

confidence: 99%

Superimposition of Pulses to Steady Arc Discharge in Toroidal Divertor Simulator

Kajita

Uchiyama

Ohno

2012

Plasma and Fusion Research

View full text Add to dashboard Cite

A pulsed discharge was superimposed to a steady state arc discharge in the toroidal divertor simulator NAGDIS-T. The dynamic response of the plasma was observed with an electrostatic probe and fast framing camera. In the first loop plasma, which is close to the plasma source, the density becomes higher in response to the pulsed discharge, and the emission from the plasma significantly increases. On the other hand, in the second loop plasma, where a recombining plasma is formed, the emission from the plasma disappears in response to the pulse. Just after the pulsed discharge, plasma instabilities were formed and they were propagated from the upstream to downstream at the velocity of ∼10 km/s. After the series of pulsed plasma experiments, arc trails were recorded around the cathode area. On a molybdenum cover of the cathode, unipolar arcing was initiated on the surface. It is likely that the pulsed discharge leads to instabilities and initiate the unipolar arcing consequently.

show abstract

“…• High electric fields produce micron-sized unipolar arc discharges [7,8]. The plasma requirements for producing a unipolar arc are not known precisely, however there seems to be a minimum surface field and plasma density.…”

Section: The Breakdown Modelmentioning

confidence: 99%

“…"The unipolar arc may be expected whenever a plasma of sufficient density and electron temperature is in contact with a metal surface of sufficient area" [8]. Although it seems to be the primary mechanism by which arcs can damage surfaces, there has been little study of this mechanism, theoretical or experimental, in the last 15 years.…”

Section: Unipolar Arc Physicsmentioning

confidence: 99%

See 1 more Smart Citation

The Problem of RF Gradient Limits

Norem

Insepov

Huang

et al. 2010

AIP Conference Proceedings

View full text Add to dashboard Cite

Abstract. We describe breakdown in rf accelerator cavities in terms of a number of mechanisms. We divide the breakdown process into three stages: 1) we model surface failure using molecular dynamics of fracture caused by electrostatic tensile stress, 2) the ionization and plasma growth is modeled using a particle in cell code, 3) we model surface damage by assuming unipolar arcing. Although unipolar arcs are strictly defined with equipotential boundaries, we find that the cold, dense plasma in contact with the surface produces very small Debye lengths and very high electric fields over a large area, and these high fields produce strong erosion mechanisms, primarily self sputtering, compatible with crater formation. We compare this model with arcs in tokamaks, plasma ablation, electron beam welding, micrometeorite impacts, and other examples.

show abstract

An Arc maintained on an Isolated Metal Plate exposed to a Plasma

Cited by 91 publications

References 1 publication

The evolution of ion charge states in cathodic vacuum arc plasmas: a review

The evolution of ion charge states in cathodic vacuum arc plasmas: a review

Superimposition of Pulses to Steady Arc Discharge in Toroidal Divertor Simulator

The Problem of RF Gradient Limits

Contact Info

Product

Resources

About