Bulletin of the American Physical Society
70th Annual Gaseous Electronics Conference
Volume 62, Number 10
Monday–Friday, November 6–10, 2017; Pittsburgh, Pennsylvania
Session TR1: Magnetically Enhanced Plasma II |
Hide Abstracts |
Chair: Charter Stinespring, West Virginia University Room: Salon D |
Thursday, November 9, 2017 4:00PM - 4:30PM |
TR1.00001: Particle-in-cell simulations of instabilities in magnetron plasmas. Invited Speaker: Denis Eremin Magnetron plasma discharges are typically used in sputtering applications, which require low (\textless 1 Pa) neutral gas pressure. This leads to electron mean free path much larger than device size, demanding a kinetic and non-local description. A popular Particle-in-cell (PIC) method employed for this purpose in its simplest variants (explicit or direct implicit schemes) has certain limitations, which encumber its use for 2d and 3d simulations of realistic cases. A novel energy-conserving implicit PIC technique enables simulations of magnetron plasmas with densities up to those observed in high-power impulse magnetron sputtering (HiPIMS) discharges. The corresponding simulations allow studying a number of pending questions concerning magnetron plasma physics. Of special interest are various instabilities arising in such type of plasmas. Leading to the so-called anomalous transport, for example, through the micro-turbulence or large nonlinearly saturated self-organized spoke structures, they are frequently critical for the discharge mere existence. The present talk will discuss observation of various instabilities in 2d and 3d PIC self-consistent simulations in magnetron discharges operated in different regimes. [Preview Abstract] |
Thursday, November 9, 2017 4:30PM - 4:45PM |
TR1.00002: Kinetic model of magnetized technological plasma Ralf Peter Brinkmann, Dennis Kr\"uger Plasma processes like magnetically enhanced reactive ion etching (MERIE), plasma ion assisted deposition (PIAD), and conventional and high power impulse magnetron sputtering (dcMS/HiPIMS) employ magnetized high density plasmas at relatively low pressures. This regime is very difficult to analyze. Fluid models do not apply and numerical kinetic approaches like particle-in-cell are rather expensive. An alternative may be ''gyrokinetics''. This theory - actually more a class of theories - was designed and successfully employed in the field of fusion plasmas. It relies on the insight that the fast gyro motion of magnetized particles can be mathematically separated from the slower drift motion and be integrated out, leaving only the dynamics on slower time scales and larger length scales. This contribution will present a gyrokinetic theory for magnetized technical plasmas that is based on first principles. The outset is a general kinetic description of the electron component, the final result is a closed system of parabolic differential equation in just two dimensions. [Preview Abstract] |
Thursday, November 9, 2017 4:45PM - 5:00PM |
TR1.00003: Analysis of the sheath model for radio frequency magnetron discharges Dennis Engel, Laura Kroll, Dennis Krueger, Ralf Peter Brinkmann Based on a global capacitive radio frequency discharge model [1], a new model for magnetron discharges has been proposed. In this model, the magnetized region is represented by a resistance, taking into account Bohm-diffusion [2].\\ Due to an asymmetric electrode configuration ($A_{grounded} >> A_{powered}$) different models for the sheath at the electrodes are implemented. The grounded electrode is represented by a DC-floating-potential and for the powered electrode the dynamic behavior of the sheath is regarded. The effects of this assumption to the new, magnetized model are discussed.\\ In the second part of this work, the sheath model itself is considered. It is assumed to be a matrix sheath. Although being a quite simple model, qualitatively good results can be obtained in comparison to experiments. Within the model the ion density is considered to be constant inside the whole sheath region, which is obviously a crude assumption. To improve this, new ion density profiles are implemented. The new voltage-charge ($V(Q)$)-characteristic is determined and the effects on the nonlinear resonance behavior are studied.\\[1ex] [1] T. Mussenbrock et al., PSST \textbf{16}, 377–385 (2007)\\{} [2] D. Bohm, The characteristics of electrical discharges in magnetic fields (1949) [Preview Abstract] |
Thursday, November 9, 2017 5:00PM - 5:15PM |
TR1.00004: Microwave Assisted Helicon Plasmas John McKee, David Caron, Andrew Jemiolo, Earl Scime The use of two (or more) rf sources at different frequencies is a common technique in the plasma processing industry to control ion energy characteristics separately from plasma generation. A similar approach is presented here with the focus on modifying the electron population in argon and helium plasmas. The plasma is generated by a helicon source at a frequency f0 $=$ 13.56 MHz. Microwaves of frequency f1 $=$ 2.45 GHz are then injected into the helicon source chamber perpendicular to the background magnetic field. The microwaves damp on the electrons via X-mode Electron Cyclotron Heating (ECH) at the upper hybrid resonance, providing additional energy input into the electrons. The effects of this secondary-source heating on electron density, temperature, and energy distribution function are examined and compared to helicon-only single source plasmas as well as numeric models suggesting that the heating is not evenly distributed. Optical Emission Spectroscopy (OES) is used to examine the impact of the energetic tail of the electron distribution on ion and neutral species via collisional excitation. Large enhancements of neutral spectral lines are observed in both Ar and He. While small enhancement of ion lines is seen in Ar, ion lines not normally present in He are observed during microwave injection. [Preview Abstract] |
Thursday, November 9, 2017 5:15PM - 5:30PM |
TR1.00005: Electron Drift Dynamics at the Plasma Boundary Sheath in Magnetized Low Temperature Plasmas Dennis Krueger, Jan Trieschmann, Ralf Peter Brinkmann Two important examples of magnetized low temperature plasmas are high power impulse magnetron sputtering (HiPIMS) and Hall-effect thrusters. Although being designed for completely different applications, similar features can be identified. Common electric and magnetic field configurations lead to various types of drifts and instabilities. One peculiar phenomenon in such discharges are rotating patterns, sometimes called spokes, which develop under certain discharge conditions. As self-organized symmetry breaking structures, these patterns can only be understood by 3d models. To formulate a consistent 3d model, an appropriate boundary condition at the plasma walls must be utilized. Therefore, we investigate the interaction of magnetized electrons with the plasma boundary sheath by means of a 3d kinetic single electron model. For two different sheath models, a specular reflection model and a more physical Bohm sheath model, we find that the effective outcome, in particular the resulting drifts of the guiding center, are very similar. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700