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

Abstract

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.

Ion velocities in direct current arc plasma generated from compound cathodes

“…17,19 The cohesive energies of the present elements are 4.85 eV (Ti), 7.37 eV (C), 3.39 eV (Al), and 4.63 eV (Si) (see Ref. 2).…”

A review comparing cathodic arcs and high power impulse magnetron sputtering (HiPIMS)

“…In the case of pulsed cathodic arcs, the ion charge states are enhanced at the beginning of each pulse [90,256], which generally correlates with higher than average kinetic energies. For HiPIMS, each pulse undergoes an evolution from gas-dominated to a metal-dominated plasma, which is well established based on time-resolved optical emission spectroscopy [257,258], mass/charge spectrometry [186,259], spectrally resolved imaging [85,258,260], and last but not least by using a rotating shutter mechanism allowing us to look directly at phased ion impact on film growth [216,217].…”

“…Pulsed cathodic arc discharges are cold-cathode arc discharges [1,88] ), where the cathode surface material is extremely rapidly transformed from solid to plasma [90] due to the combined action of ion bombardment and Joule (Ohmic) heating. Plasma parameters (and related information) of cathodic arcs are listed in Table 1 for comparison with other processes.…”

Ion Charge State Distributions of Al and Cr in Cathodic Arc Plasmas From Composite Cathodes in Vacuum, Argon, Nitrogen, and Oxygen

“…I N THE past two decades much effort was made to study the distribution of the ion charge states in the vacuum arc plasma of nearly all metals in the periodic table, see, for example, experiments in [1]- [3], a theoretical consideration [4], [5], and a recent review [6]; many more references will be cited later in this paper. In addition to these ion charge state distributions (ICSDs) under rather basic conditions, the effects of the arc current level, the strength of an optional magnetic field, the pressure and kind of background gas, and the distance from the plasma-producing cathode spot are investigated in great detail (for an overview, see [6]- [8]).…”