Download Plasma E- Measurement

Plasma EMeasurement
Brian DeHerrera
John Purcell
Jaber Assiri
Outline

Introduction
◦ Purpose
◦ Problems




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HFSS Simulation
Current Design
Voltage Divider
Future Work & budget
Conclusion
Purpose

Create reliable current and voltage
sensing equipment to work in common
plasma ranges
◦ >500V
◦ >10MHz

Create more reliable plasma for
experiments
◦ Control line impedance
◦ Measure waveform being transmitted to plasma
probe
Plasma System
Signal
Generator
Amplifier
ZScan
Matching
Network
Plasma
Probe
Problems

No commercially available probes
◦ Can meet some specifications, but not both
frequency and desired voltage

Not trivial to create homebrew probe
◦ Needs to be high impedance
◦ Parasitic
HFSS Simulation


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

Draw Model
Assign Boundary Conditions
Assign Excitation Ports (inputs)
Analyze
Generate Reports
Draw Model
Freq Response
Current Design: Coax
Modeled design off of AE’s Z-Scan
Benefits:
 Parasitic are minimized
 Sensor can be added in-line with plasma
system
Concerns:
 EMI design: both shielding outside noise
and reducing leakage
 Semi-complicated design
◦ Need to machine parts
Current Design: Coax
Signal
Generator
Amplifier
ZScan
Matching
Network
COAX
device
Plasma
Probe
Current Design: Coax
Voltage Divider

Why a V-D?
Voltage Divider

Conditions:
◦ R1+R2>= 2M Ohm & C1+C2<10p F
Signal
Generator
Amplifier
Z-Scan
Matching
Network
Plas
ma
Prob
e
Voltage Divider

Conditions:
◦ R1*C1=R2*C2
 If (R1*C1)> (R2* C2)
Voltage Divider

Conditions:
◦ R1*C1=R2*C2
 If (R1*C1)<(R2* C2)
Voltage Divider

Conditions:
◦ R1*C1=R2*C2
Voltage Divider

From:
◦ R1+R2>= 2M Ohm & C1+C2<10pF
&
◦ R1*C1=R2*C2

Therefore:
◦ R1= 10M ohm, R2= 100k ohm
◦ C1= .1pF , C2= 10pF
Future Work
Date
What will be done
Cost
1/30/2010
Finish the designs we
have
Find more sensitive
Current Transformer
& probes
Getting some
readings
$120
2/15/2010
Change the important
changes in the designs
$10-$20
3/1/2010
Getting some results
3/30/2010
Start to do the final
designs
2/1/2010
2/10/2010
$10-$50
Conclusion





Purposes & problems
HFSS Simulation
Current Design
Voltage Divider
Future Work & budget
Thank you

Questions ??