Fast charge exchange ions in high power impulse magnetron sputtering of titanium as probes for the electrical potential

Breilmann, Wolfgang; Maszl, Christian; Keudell, Achim von

doi:10.1088/1361-6595/aa56e5

Cited by 14 publications

(17 citation statements)

References 22 publications

(34 reference statements)

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“…At higher pressures, the Ti + spectral line intensity increases with increasing the discharge current up to 125 A. The decrease of the Ti + spectral line intensity with increasing the discharge cur rent was attributed to the strong ionization of the sputtered species in the magnetized plasma, leading to a significant creation of multiply charged Ti ions similar to [37][38][39]. The appearance of the round spokes correlates with the experimental conditions where multiple ionized metal ions become dominant.…”

Section: Discussion On Spoke Shapementioning

confidence: 77%

Effect of magnetic field on spoke behaviour in HiPIMS plasma

Hnilica¹,

Klein²,

Šlapanská³

et al. 2018

J. Phys. D: Appl. Phys.

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The objective of this paper is to study the effect of magnetic field strength on spoke behaviour in a high power impulse magnetron sputtering discharge. In three magnetic field configurations, a broad range of experimental conditions was investigated by high-speed camera imaging. The dual image feature of the employed camera enabled us to determine the shape and spoke mode number, as well as the velocity of the spokes. Five distinct spoke shapes were detected. For each magnetic field, a map was created relating the occurrence of the spoke shape with the discharge conditions. Similarly, the spoke mode number, as well as the spoke velocity, was found to be strongly dependent on the discharge conditions. Based on the optical emission results, it was proposed that the trailing edge of the triangular spoke is related to the production of secondary electrons created by argon ions on the spoke edges, while in the case of a round spoke shape, the secondary electrons are mainly created by multiple charged titanium ions in the centre of the spoke.

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Section: Discussion On Spoke Shapementioning

confidence: 77%

Effect of magnetic field on spoke behaviour in HiPIMS plasma

Hnilica¹,

Klein²,

Šlapanská³

et al. 2018

J. Phys. D: Appl. Phys.

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“…Furthermore, this small portion does not seemingly play a significant role in the spoke dynamics. Ti II decreases at the trailing edge of the spoke (figure 9(d)), which indicates stronger ionisation and creation of multiply charged Ti ions [67][68][69]. To elaborate why we do not see such an effect on Ti I, we need to establish that the ionelectron cross-section is, in general, a few orders of magnitude higher compared to neutral-electron [70,71].…”

Section: Evolution Of Selected Spectral Line Intensitiesmentioning

confidence: 96%

Single-shot spatial-resolved optical emission spectroscopy of argon and titanium species within the spoke

Šlapanská¹,

Kroker²,

Hnilica³

et al. 2021

J. Phys. D: Appl. Phys.

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The rotating plasma patterns, also known as ionisation zones or spokes, observed, among other discharges, in high power impulse magnetron sputtering discharge (HiPIMS) require non-invasive diagnostics favourable for a precise characterisation of their properties. In this contribution, the single-shot spatial-resolved optical emission spectroscopy of the spoke was conducted in non-reactive HiPIMS discharge using a titanium target. Investigated working pressures cover the conditions with the presence of localised, well-defined spokes. A fast photodiode and a cylindrical Langmuir probe were utilised to capture and determine the passing spoke position. These signals were synchronised with the acquisition of the optical emission spectrum by the intensified charge-coupled device detector. A large amount of single-shot data enabled the statistical analysis of the spoke. The optical emissions of argon atoms and ions and titanium atoms and ions were investigated in the passing spoke. It was found that the intensities of the spectral lines of the Ar and Ti species have the characteristic evolution for all studied spectral lines of this specific species within the spoke. The intensity evolutions are independent of the applied pressure. The evolution of the excitation temperatures determined by the Boltzmann plot method using the Ar II and Ti I and Ti II spectral lines remains constant within the spoke in the margin of standard error for all investigated pressures.

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“…These bright spots have been coined spokes, in resemblance to similar features found in Hall thrusters [7]. Spokes have been investigated both in terms of their properties like velocity [7][8][9], shape [6,7,9,10] and mode number [6,7,9] and also in terms of their influence on ion transport [11][12][13][14][15][16]. All these experiments base their analysis on time averaged data or on time-resolved data that was recorded outside of the spokes.…”

Section: Introductionmentioning

confidence: 99%

Electron density, temperature and the potential structure of spokes in HiPIMS

Held

Maaß

Gathen

et al. 2020

Plasma Sources Sci. Technol.

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In high power impulse magnetron sputtering (HiPIMS) bright plasma spots are observed during the discharge pulses that rotate with velocities in the order of 10 km s−1 in front of the target surface. It has proven very difficult to perform any quantitative measurements on these so-called spokes, which emerge stochastically during the build-up of each plasma pulse. In this paper, we propose a new time shift averaging method to perform measurements integrating over many discharge pulses, but without phase averaging of the spoke location, thus preserving the information of the spoke structure. This method is then applied to perform Langmuir probe measurements, employing magnetized probe theory to determine the plasma parameters inside the magnetic trap region of the discharge. Spokes are found to have a higher plasma density, electron temperature and plasma potential than the surrounding plasma. The electron density slowly rises at the leading edge of the spoke to a maximum value of about 1 × 1020 m−3 and then drops sharply at the trailing edge to 4 × 1019 m−3. The electron temperature rises from 2.1 eV outside the spoke to 3.4 eV at the trailing end of the spoke. A reversal of the plasma potential from about −7 V outside the spoke to values just above 0 V in a spoke is observed, as has been proposed in the literature.

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Fast charge exchange ions in high power impulse magnetron sputtering of titanium as probes for the electrical potential

Cited by 14 publications

References 22 publications

Effect of magnetic field on spoke behaviour in HiPIMS plasma

Effect of magnetic field on spoke behaviour in HiPIMS plasma

Single-shot spatial-resolved optical emission spectroscopy of argon and titanium species within the spoke

Electron density, temperature and the potential structure of spokes in HiPIMS

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