On the random walk of arc cathode spots in vacuum

Hantzsche, E.; Jüttner, B.; Pursch, H.; Daalder, J.E.

doi:10.1088/0022-3727/16/9/002

Cited by 31 publications

(18 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Last but not least, the patterns seen in light emission and left on cathode surface are "tree-branched" -a typical self-similar pattern [24,26]. Clearly, there is a relation to the apparent motion of cathode spots, which in the absence of a magnetic field can be modeled by random walk [27][28][29]. The fractal properties can be recorded using the streak camera technique (Fig.…”

Section: Fractal Cathode Spotsmentioning

confidence: 99%

“…Even as only a small percentage of ions do not stick, the flux of atoms (i.e., neutralized former ions) from the surface causes a very relevant density according to   1 a c ii a n S nv v   (28) since the characteristic atom velocity a v is much smaller than the characteristic ion velocity i v . Nonsticking necessarily produces neutrals, and charge exchange reactions (27) occur, predominantly reducing the fraction of higher charged ions and producing more singly charged ions, in agreement with measurements [100,102].…”

Section: Charge Exchange Collisionsmentioning

confidence: 99%

See 1 more Smart Citation

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: Fractal Cathode Spotsmentioning

confidence: 99%

Section: Charge Exchange Collisionsmentioning

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

“…Over many years, pieces of evidence for fractal features of cathode phenomena have emerged [6][7][8][9][10][11]. At the same time, much research was done in the field of deterministic chaos and fractals [4,5].…”

Section: Fractal Approach To Cathode Spotsmentioning

confidence: 99%

“…Daalder [7] and Hantzsche and co-workers [6] established that in the absence of an external magnetic field, spot motion may be modeled as random walk. One may assume that each displacement occurs in a small elementary step, s, which takes an average elementary time τ .…”

Section: Ms#tps0860r1 --Lbnl-56776 --(I) Random Walk Of Cathode Spotsmentioning

confidence: 99%

“…In the literature, random walk of cathode spots has been analyzed with the assumption of a constant elementary step s. Hantzsche and co-workers [6] suggested using the mean crater radius as the elementary step length for type 2 spots based on analysis of arc traces on clean metal surfaces. The assumption is justified by the appearance of crater chains, though its general validity was disputed by Daalder [43] because, so he argued, one can also observe separated craters, which are usually associated with type 1 spots.…”

Section: Ms#tps0860r1 --Lbnl-56776 --(I) Random Walk Of Cathode Spotsmentioning

confidence: 99%

See 1 more Smart Citation

The fractal nature of vacuum arc cathode spots

Anders

2005

IEEE Trans. Plasma Sci.

View full text Add to dashboard Cite

Cathode spot phenomena show many features of fractals, for example self-similar patterns in the emitted light and arc erosion traces. Although there have been hints on the fractal nature of cathode spots in the literature, the fractal approach to spot interpretation is underutilized. In this work, a brief review of spot properties is given, touching the differences between spot type 1 (on cathodes surfaces with dielectric layers) and spot type 2 (on metallic, clean surfaces) as well as the known spot fragment or cell structure.

show abstract

Arc Cathode Processes in the Transition Region between Vacuum Arcs and Gaseous Arcs

Anders

Jüttner

1987

Contrib Plasma Phys

View full text Add to dashboard Cite

The cathode processes of electric arcs on cleaned Cu cathodes were investigated in the transition region between vacuum and atmospheric pressure (argon). The plasma density in the cathode plane was estimated by probe measurements to be n = (3 x 1012 A-l m-l) IA/r2 ( I A -arc current, r -distance from the spot). It was observed that several cathode spot parameters have an extremum at p cu 1oP Pa. The crater diameter has a minimum independently of the cathode temperature. The diffusion constant of the chaotic motion determined by framing photographs was found to have a maximum. Some additional, large displacements occurred a t that pressure. The diameter of the bright plasma cloud obtained by open-shutter photographs showed a maximum, the current per spot was found to decrease from 20 A in vacuum to 10 A at atmospheric pressure. It is thus concluded that the spot with the smallest crater radius and a low current per spot, occurring at -104 Pa, represents the single spot, whereas the spot a t higher pressures, and probably also in vacuum, has a complicated nature where the large craters are formed by a cooperation of single spots.

show abstract

On the random walk of arc cathode spots in vacuum

Abstract: The theoretical basis of the random walk movement of cathode arc spots is reconsidered, and the probable causes of some discrepancies in measured spot movement parameters and in their interpretation are discussed.

Cited by 31 publications

References 7 publications

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

The fractal nature of vacuum arc cathode spots

Arc Cathode Processes in the Transition Region between Vacuum Arcs and Gaseous Arcs

Contact Info

Product

Resources

About