Bulletin of the American Physical Society
69th Annual Gaseous Electronics Conference
Volume 61, Number 9
Monday–Friday, October 10–14, 2016; Bochum, Germany
Session DT1: Electrical Diagnostics IFocus
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Chair: Yevgeny Raitses, Princeton Plasma Physics Laboratory Room: 1 |
Tuesday, October 11, 2016 8:30AM - 9:00AM |
DT1.00001: RF inductive probe to measure plasma complex conductivity Invited Speaker: Alan Howling A method for measuring plasma complex electrical conductivity is described by which plasma parameters such as the electron density and the electron-neutral collision frequency can be estimated. The method relies on the measurement of the impedance of an inductive element coupled to the plasma by mutual induction. The mutual inductance due to the plasma coupling is interpreted by applying the complex image method to the plasma medium [1]; it is determined by the plasma skin depth and the distance to the plasma. For high frequency measurements, capacitive coupling must also be accounted for as a first order correction for standing wave (transmission line) effects. It is shown that a hybrid resonant network configuration can be designed to maximize the inductive coupling and minimize the capacitive coupling. [1] Ph. Guittienne, R. Jacquier, A. A. Howling and I. Furno, Plasma Sources Sci. Technol. Vol. 24, 065015 (2015). [Preview Abstract] |
Tuesday, October 11, 2016 9:00AM - 9:15AM |
DT1.00002: Active Plasma Resonance Spectroscopy: Evaluation of a fluiddynamic-model of the planar multipole resonance probe using functional analytic methods Michael Friedrichs, Ralf Peter Brinkmann, Jens Oberrath Measuring plasma parameters, e.g. electron density and electron temperature, is an important procedure to verify the stability and behavior of a plasma process. For this purpose the multipole resonance probe (MRP) represents a satisfying solution to measure the electron density. However the influence of the probe on the plasma through its physical presence makes it unattractive for some processes in industrial application. A solution to combine the benefits of the spherical MRP with the ability to integrate the probe into the plasma reactor is introduced by the planar model of the MRP. By coupling the model of the cold plasma with the maxwell equations for electrostatics an analytical model for the admittance of the plasma is derivated[1 , 2], adjusted to cylindrical geometry and solved analytically for the planar MRP using functional analytic methods. [1]: M. Lapke et al. , Plasma Sources Sci. Technol. 22 (2013) 025005 (8pp) [2]: J. Oberrath, R.P. Brinkmann, Plasma Sources Sci. Technol. 23 (2014) 065025 (10pp) [Preview Abstract] |
Tuesday, October 11, 2016 9:15AM - 9:30AM |
DT1.00003: Collisionless Spectral Kinetic Simulation of Ideal Multipole Resonance Probe Junbo Gong, Sebastian Wilczek, Daniel Szeremley, Jens Oberrath, Denis Eremin, Wladislaw Dobrygin, Christian Schilling, Michael Friedrichs, Ralf Peter Brinkmann \textit{Active Plasma Resonance Spectroscopy} denotes a class of industry-compatible plasma diagnostic methods which utilize the natural ability of plasmas to resonate on or near the electron plasma frequency $\omega_{\rm{pe}}$. One particular realization of \textit{APRS} with a high degree of geometric and electric symmetry is the \textit{Multipole Resonance Probe (MRP)}. The Ideal \textit{MRP(IMRP)} is an even more symmetric idealization which is suited for theoretical investigations. In this work, a spectral kinetic scheme is presented to investigate the behavior of the \textit{IMRP} in the low pressure regime. However, due to the velocity difference, electrons are treated as particles whereas ions are only considered as stationary background. In the scheme, the particle pusher integrates the equations of motion for the studied particles, the Poisson solver determines the electric field at each particle position. The proposed method overcomes the limitation of the cold plasma model and covers kinetic effects like collisionless damping. [Preview Abstract] |
Tuesday, October 11, 2016 9:30AM - 9:45AM |
DT1.00004: Electron density measurements in very electronegative plasmas using different diagnostic techniques: theory and experiments Dmytro Rafalskyi, Trevor Lafleur, Ane Aanesland Very electronegative plasmas (known as ``ion-ion'' plasmas) are used in different applications including material processing, space propulsion and thermonuclear fusion. Diagnostics of ion-ion plasmas can be performed using different probe techniques, including Langmuir and hairpin probes, RF, microwave and optical diagnostics. However, in certain applications (for example, in the electronegative thruster PEGASES [\textit{Plasma Sources Sci. Technol.} \textbf{23} 044003 (2014)]), the electron density is too low (\textless 10$^{\mathrm{12}}$m$^{\mathrm{-3}})$ to be reliably measured by these standard techniques. This is further complicated by the presence of strong, non-homogeneous, magnetic fields in the plasma (\textasciitilde 200 G) and the relatively small plasma size (few cm). In this work we compare results achieved with a Langmuir probe, and with an independent measurement of the electron density using a matched dipole probe [\textit{Phys. Plasmas},~\textbf{22}, 073504 (2015)]. Measurements are performed in an SF6 plasma with an electronegativity in the range between a few hundred to a few thousand. We show here that though the model itself can correctly describe the plasma-probe interactions, there is a critical value of plasma electronegativity above which the electron density measured with a Langmuir probe can give only an upper limit estimation. [Preview Abstract] |
Tuesday, October 11, 2016 9:45AM - 10:00AM |
DT1.00005: Measurement Of Plasma Parameters In Micro-Discharge By Wall Probe Almaz Saifutdinov, Anatoly Kudryavtsev, Sergey Sysoev The increasing scientific and practical interest for glow discharge at high pressure is largely determined by the fact that their use does not require expensive and huge vacuum equipment. The analysis shows that, in contrast to the well-studied positive column (PC), the basic parameters of the plasma negative glow (NG) and Faraday dark space (FDS) of micro-discharges are studied insufficiently. The difficulties of the experimental diagnostics are associated with the fact that for the fixed values of \textit{pL} with the increasing gas pressure the length of the micro-discharge decreases. And a small size is extremely difficult to diagnose spatial parameters distribution of micro discharges. Since at a small size introducing traditional Langmuir probe into the plasma capacity is not possible technically, it was proposed to use an additional measuring electrode (wall probe) disposed between the cathode and the anode for measurement of the fast EEDF. With its use we have registered EEDF fast electrons produced in the reaction of Penning ionization out of earlier reach range of high-pressure gas (from 20 to 200 Torr). In this paper by using wall probe we measured the basic parameters of NG plasma in micro-discharge in helium in a wide range of pressures. It is shown that the electrons temperature in the NG plasma is low and amounts to few fraction of 1 eV, which differs from the electron temperature in PC plasma. This allows the use of NG plasma for analysis by gas plasma electron spectroscopy. [Preview Abstract] |
Tuesday, October 11, 2016 10:00AM - 10:15AM |
DT1.00006: Combined complementary plasma diagnostics to characterize a 2f plasma with additional DC current with conditioning effects at the chamber wall Michael Klick, Ralf Rothe, Kye Hyun Baek, Eunwoo Lee Multiple frequencies and DC current used in a low-pressure plasma rf discharge result in an increased complexity. This needs plasma diagnostics applied, in particular in a plasma process chamber. That is done under manufacturing conditions which restrict the applicable plasma diagnostics to non-invasive methods with small footprint. So plasma chamber parameters, optical emission spectroscopy (OES), and self-excited electron spectroscopy (SEERS) are used to characterize the plasma and to understand chamber wall conditioning effects in an Ar plasma. The parameters are classified according to their origin – the region they are representative for. The center ion density is estimated from the DC current and compared to the SEERS electron density reflecting the electron density close to that at the chamber wall. The conditioning effects are caused by Si sputtering at a Si wafer changing the chamber wall state only when the chamber is clean, subsequent plasmas in the same chamber are not affected in that way. Through the combination of the complementary methods it can be shown that the chamber wall condition finally changes the radial plasma density distribution. Also the heating of electrons in the sheath is shown to be influenced by conditioning effects. [Preview Abstract] |
Tuesday, October 11, 2016 10:15AM - 10:30AM |
DT1.00007: MOVED TO DT1:6 |
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