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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2742
DTSTART:20121116T213000Z
DURATION:PT1H0M0S
DTSTAMP:20260415T023714Z
LAST-MODIFIED:20121023T152823Z
LOCATION:2241 Chamberlin Hall (coffee at 4:30 pm)
SUMMARY:Physics at the edge: Plasmas with dynamic sheaths\, Physics De
 partment Colloquium\, Uwe Czarnetzki\, Ruhr University Bochum
DESCRIPTION:Plasmas generated by applying a radio-frequency potential 
 across a gas at low pressure between two electrodes are called capacit
 ively coupled plasmas (CCP). They find frequent application in semicon
 ductor and solar-cell production and other fields of industry. The phy
 sics of CCPs is dominated by the non-linear dynamics of the space-char
 ge sheaths in front of the electrodes. This dynamics determines the io
 n as well as the electron energy distribution function\, provides the 
 main stochastic electron heating mechanism\, and is also essential for
  trapping of energetic electrons. If a certain asymmetry between the s
 heaths at the two electrodes exists\, the non-linearity leads to self-
 generated high frequency current oscillations which can strongly enhan
 ce the electron heating.  Usually the asymmetry results from the geome
 trical size of the electrodes. However\, by applying non-sinusoidal wa
 veforms the symmetry can be broken even in the case of geometrical sym
 metry. This so called aEurooeelectrical asymmetry effectaEuro provides
  a simple and elegant way of external control where in particular the 
 ion energy can be adjusted. The underlying physics will be explained b
 y experimental results\, analytical models\, and particle-in-cell/Mont
 e-Carlo simulations. 
URL:https://www.physics.wisc.edu/events/?id=2742
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