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A high power impulse magnetron sputtering (HiPIMS) discharge assisted by a dc pre-ionizer operating at low pressure has been investigated using the Langmuir probe technique as well as energy-resolved mass spectrometry. It was found that the background plasma with densities of about 1 × 109 cm-3 provided by the dc pre-ionizer can reduce the ignition delay time of the HiPIMS plasma from more than 50 μs to less than 5 μs at a working pressure of about 0.1 Pa. Furthermore, the technique of super-imposing HiPIMS with the dc discharge can be readily employed with a low self-sputtering yield target (Ti) at a working pressure of 0.08 Pa, with a pulse width and a repetition frequency of 100 μs and 100 Hz, respectively. This leads to a power density of 450 Won 2 at the target. At these operating conditions, the probe measurements showed a high-density plasma 6 cm in front of the target. The maximum electron density was found to be 8 × 1011 cm-3, with an effective electron temperature of about 3-4 eV. A study of the ion mass distribution revealed that the intensity of Ti2+ ions is larger than the peak of Ti+ in low-pressure operation. Moreover, the number of metal ions in the high-energy tail of the ion energy distribution function increased with a decreasing pressure from 0.5 to 0.08 Pa.

6 pags, 7 figs, 3 tabs, A dielectric barrier discharge (DBD) technique has been employed to produce uniform atmospheric plasmas of He and N2 gas mixtures in open air in order to functionalize the surface of filtered-arc deposited hydrogen-free diamond-like carbon (DLC) films. XPS measurements were carried out on both untreated and He/N2 DBD plasma-treated DLC surfaces. Chemical states of the C 1s and N 1s peaks were collected and used to characterize the surface bonds. Contact angle measurements were also used to record the short- and long-term variations in wettability of treated and untreated DLC. In addition, cell viability tests were performed to determine the influence of various He/N2 atmospheric plasma treatments on the attachment of osteoblast MC3T3 cells. Current evidence shows the feasibility of atmospheric plasmas in producing long-lasting variations in the surface bonding and surface energy of hydrogen-free DLC and consequently the potential for this technique in the functionalization of DLC-coated devices. © 2008 Elsevier B.V. All rights reserved., Financial support from the Marie Curie Outgoing Fellowship Grant MOIF-CT-2005-02195 is gratefully acknowledged. Work at Lawrence Berkeley National Laboratory was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Financial support from the Spanish Ministry of Education under project MAT2004-01451 is also gratefully acknowledged

Using a biased quartz crystal microbalance in combination with a gridded electrode, the ionized metal flux fraction in a high power impulse magnetron sputtering (HiPIMS) discharge operated with a titanium target has been investigated. The average discharge power was controlled by varying three different parameters; initial target voltage, pulse width and pulse frequency. The average discharge power was varied from 0.3 to 1.3 kW and irrespective of the power control method used an associated decrease in the flux fraction (from 50% to 30%) was observed. The mechanisms responsible for this decrease in the time-averaged flux fraction of metal ions are discussed.