Arc Discharge

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Arc Discharge
EE 403/503 Introduction to Plasma Processing
October 29 2008
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V-I Characteristic of DC Discharges
1000 V
Background Ionization
Glow Discharge
Arc Discharge
Townsend Discharge
Glow to Arc Transition
Breakdown Voltage
500
Abnormal Glow
Thermal
Normal Glow
Non- Thermal
0
1
10-8
10-4
104A
10-6
10-2
102
10-10
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Jens Wendelstorf TU Braunschweig
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Anode
Cathode
Arc Column
Cathode Sheath
Cathode Region
Anode Flow Zone
Anode Region
Anode Sheath
Cathode Flow Zone
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Arc Dynamics
R
rltR
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Example
I 200 A 0.015 Kg/m3 j 4.5 x 107 A/m2 V
350 m/s
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Electrical Stability Criteria
i1
i3
i2
V0v x i2
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V-I Characteristic of DC Discharges
1000 V
Background Ionization
Glow Discharge
Arc Discharge
Townsend Discharge
Glow to Arc Transition
VI-Characteristics Of the Power Source
Breakdown Voltage
500
C
A
B
D
E
Abnormal Glow
Thermal
Normal Glow
Non- Thermal
0
1
10-8
10-4
104A
10-6
10-2
102
10-10
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Linear homogeneous second-order differential
equation
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Solution
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Stable solution when
1- The criterion that RltL/(vC) is usually
met 2- vgt0 every intercept of the load line
with the arc characteristic leads to a stable
point. 3- vlt0 stable point when Rgtv -gt Load
line must intercept the characteristic line from
above
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1000 V
Background Ionization
Glow Discharge
Arc Discharge
Townsend Discharge
Glow to Arc Transition
VI-Characteristics of the Power Source
Breakdown Voltage
500
C
A
B
D
E
Abnormal Glow
Normal Glow
Thermal
Non- Thermal
0
1
10-8
10-4
104A
10-6
10-2
102
10-10
1- vgt0 every intercept of the load line with
the arc characteristic leads to a stable point. A
C 2- vlt0 stable point when Rgtv -gt Load
line must intercept the characteristic line from
above B D are not E is (The criterion that
RltL/(vC) is usually met)