Electron Emission from Surfaces Induced by Slow Ions and Atoms

Baragiola, R. A.; Riccardi, P.

doi:10.1007/978-3-540-76664-3_2

Cited by 18 publications

(20 citation statements)

References 62 publications

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“…The bias current I bias can be regarded as an easy to measure approximate quantity describing the flux of incident ions, which are usually single positive charged. However, besides the actual ion current, I bias also comprises a superimposed current due to the emission of secondary electrons [34]. As is to be expected, the statistical evaluation (Figure 5c) proves that, in the first place, I bias depends on a positive effect of its cause, U bias (B).…”

Section: Bias Currentsupporting

confidence: 62%

Empirical-Statistical Study on the Relationship between Deposition Parameters, Process Variables, Deposition Rate and Mechanical Properties of a-C:H:W Coatings

et al. 2014

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Tungsten-modified hydrogenated amorphous carbon coatings (a-C:H:W) were deposited on high speed steel by reactive magnetron sputtering of a tungsten carbide target in an argon-ethine atmosphere. The deposition parameters, sputtering power, bias voltage, argon and ethine flow rate, were varied according to a central composite design comprising 25 different parameter combinations. For comparison, a tungsten carbide coating was deposited, as well. During coating deposition, the process variables, total pressure, sputtering voltage and bias current, were measured as process characteristics. The thickness of the deposited coatings was determined using the crater grinding method, and the deposition rate was calculated. Young's modulus E and indentation hardness H IT were characterized by means of nanoindentation. With E = 80 − 253 GPa and H IT = 7.8 − 22.0 GPa, the mechanical properties were found to vary strongly in between different a-C:H:W variants. Using statistical methods, it is shown that these properties, as well as the deposition rate significantly depend on all four varied parameters. Despite a very similar influence of the parameters on modulus and hardness, as well as a very strong correlation of both properties, it is pointed out statistically that the H/E ratio, which is an indicator of the wear resistance, can be adapted in a targeted way and with some degree of independence.

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Section: Bias Currentsupporting

confidence: 62%

Empirical-Statistical Study on the Relationship between Deposition Parameters, Process Variables, Deposition Rate and Mechanical Properties of a-C:H:W Coatings

et al. 2014

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“…For a potential emission to occur the potential energy (ionization potential) of the projectile has to exceed twice the work function of the target material. A fit to experimentally determined secondary electron emission yield for various ions on clean surfaces is given as 208,209 c SE ¼ 0:032ð0:78E iz À 2/Þ; (15) where E iz is the neutralization energy of the ion and / is the work function of the target surface. The process can only occur if 0.78E iz > 2/.…”

Section: Self-sputteringmentioning

confidence: 99%

High power impulse magnetron sputtering discharge

Guðmundsson¹,

Brenning²,

Lundin³

et al. 2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

637

446

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The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulses at low duty cycle and low repetition frequency while keeping the average power about 2 orders of magnitude lower than the peak power. This results in a high plasma density, and high ionization fraction of the sputtered vapor, which allows better control of the film growth by controlling the energy and direction of the deposition species. This is a significant advantage over conventional dc magnetron sputtering where the sputtered vapor consists mainly of neutral species. The HiPIMS discharge is now an established ionized physical vapor deposition technique, which is easily scalable and has been successfully introduced into various industrial applications. The authors give an overview of the development of the HiPIMS discharge, and the underlying mechanisms that dictate the discharge properties. First, an introduction to the magnetron sputtering discharge and its various configurations and modifications is given. Then the development and properties of the high power pulsed power supply are discussed, followed by an overview of the measured plasma parameters in the HiPIMS discharge, the electron energy and density, the ion energy, ion flux and plasma composition, and a discussion on the deposition rate. Finally, some of the models that have been developed to gain understanding of the discharge processes are reviewed, including the phenomenological material pathway model, and the ionization region model.

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“…The yields of secondary electrons emitted from (clean) metal surfaces from the impact of hydrogen ions with kinetic energies of 2 to 10 keV increase from 0.45 to 1.25 electrons/ion (for molybdenum) [42]. But secondary electron emission is very sensitive to the surface work function (or electron affinity for oxides) and the electronic energy loss of ions (which depends on the target composition) both of which were not measured during our experiments [43]. This could lead to an uncertainty in the ion currents between low and high cathode voltages of up to an estimated factor of two.…”

Section: Neutron Yield Results and Discussionmentioning

confidence: 99%

Investigation of light ion fusion reactions with plasma discharges

Schenkel

Persaud

Wang

et al. 2019

Journal of Applied Physics

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The scaling of reaction yields in light ion fusion to low reaction energies is important for our understanding of stellar fuel chains and the development of future energy technologies. Experiments become progressively more challenging at lower reaction energies due to the exponential drop of fusion cross sections below the Coulomb barrier. We report on experiments where deuterium-deuterium (D-D) fusion reactions are studied in a pulsed plasma in the glow discharge regime using a benchtop apparatus. We model plasma conditions using particle-in-cell codes. Advantages of this approach are relatively high peak ion currents and current densities (0.1 to several A/cm 2 ) that can be applied to metal wire cathodes for several days. We detect neutrons from D-D reactions with scintillator-based detectors. For palladium targets, we find neutron yields as a function of cathode voltage that are over 100 times higher than yields expected for bare nuclei fusion at ion energies below 2 keV (center of mass frame). A possible explanation is a correction to the ion energy due to an electron screening potential of 1000±250 eV, which increases the probability for tunneling through the repulsive Coulomb barrier. Our compact, robust setup enables parametric studies of this effect at relatively low reaction energies.

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Electron Emission from Surfaces Induced by Slow Ions and Atoms

Cited by 18 publications

References 62 publications

Empirical-Statistical Study on the Relationship between Deposition Parameters, Process Variables, Deposition Rate and Mechanical Properties of a-C:H:W Coatings

Empirical-Statistical Study on the Relationship between Deposition Parameters, Process Variables, Deposition Rate and Mechanical Properties of a-C:H:W Coatings

High power impulse magnetron sputtering discharge

Investigation of light ion fusion reactions with plasma discharges

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