non-monotonic distributions of excited atoms in positive column of he discharges: dynamic plasma
DESCRIPTION
DOE Plasma Science Center Control of Plasma Kinetics. NON-MONOTONIC DISTRIBUTIONS OF EXCITED ATOMS IN POSITIVE COLUMN OF He DISCHARGES: DYNAMIC PLASMA. Simulation: Different Stages of Positive Column in Pulsed Current Regimes. - PowerPoint PPT PresentationTRANSCRIPT
NON-MONOTONIC DISTRIBUTIONS OF EXCITED ATOMS INPOSITIVE COLUMN OF He DISCHARGES: DYNAMIC PLASMA
DOE Plasma Science CenterControl of Plasma Kinetics
HIGHLIGHT
Radial distribution of excited atoms for different pressure and time during the current pulse.
Simulation: Different Stages of Positive Column in Pulsed Current Regimes
· Nonmonotonic radial distributions of excited helium have been experimentally observed in a pulsed positive column using laser induced fluorescence. Simulations indicate a “dynamic discharge” regime with peculiar properties.
r/r0
-0.5 0.0 0.5
Exc
ited s
tate
de
nsi
ty
0.0
0.2
0.4
0.6
0.8
1.0
11.2 Torr-cm 10 Torr-cm
5.6 Torr-cm 5 Torr-cm
2.3 Torr-cm 1 Torr-cm
Early
Later
Measured 23P Simulated 23S
Cu
rre
nt (A
)
0.0
0.5
1.0
E (
V/c
m)
0
5
10
Time (s)
-50 0 50 100 150 200
kTe (
eV
)
0123
3 Torr-cm, 0.3 Amp10 Torr-cm, 1 Amp
E0
kTe0
(1) (2) (3) (4)
I0
QUASI-PERIODIC MODE HOPPING INCOMPETING IONIZATION WAVES
DOE Plasma Science CenterControl of Plasma KineticsPLSC_0213 HIGHLIGHT
· Neon-ionization-wave normal modes compete as coupled spatiotemporal oscillators modulated by resonant laser light chopped almost synchronously with the subdominant wave mode resulting in indefinite mode hopping.
· The mode-amplitude normalization of the driving term in the differential equations, inherent in driven-oscillator phenomena and responsible for quasi-periodic mode hopping, is validated by experimental observations.
· Amount that spatiotemporal driving-force amplitude MST exceeds temporal driving-force amplitude MT increases as the spatiotemporal entrainment threshold is approached.