NON-MONOTONIC DISTRIBUTIONS OF EXCITED ATOMS IN
POSITIVE COLUMN OF He DISCHARGES: DYNAMIC PLASMA
2.3 Torr-cm
Excited state density
5.6 Torr-cm
1 Torr-cm
5 Torr-cm
1.0
0.8
0.4
0.0
(2)
(3)
(4)
0.5
0.0
10
10 Torr-cm, 1 Amp
3 Torr-cm, 0.3 Amp
I0
E0
5
0
3 kTe0
2
1
0
-50
0
50
100
150
200
Time (s)
0.6
0.2
Current (A)
Later
E (V/cm)
Early
(1)
1.0
kTe (eV)
Measured 23P Simulated 23S
11.2 Torr-cm
-0.5
0.0
10 Torr-cm
0.5
r/r0
Radial distribution of excited
atoms for different pressure and
time during the current pulse.
HIGHLIGHT
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.
DOE Plasma Science Center
Control of Plasma Kinetics
QUASI-PERIODIC MODE HOPPING IN
COMPETING IONIZATION WAVES
 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 quasiperiodic 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.
PLSC_0213
HIGHLIGHT
DOE Plasma Science Center
Control of Plasma Kinetics