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Langmuir probe chara with Model 6487

2502, 6485, 6487 - Support
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venuanand
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Joined: May 12th, 2014, 10:50 pm
Country: India

Langmuir probe chara with Model 6487

Post by venuanand » September 16th, 2014, 5:27 am

Hi
I am trying to plot the langmuir probe chara (IV) of a discharge tube using 6487. However one of the electrodes of the discharge tube is already connected to the ground(global/chassis). How should I connect 6487 voltage source and - to the probe?

Dale C
Keithley Applications
Keithley Applications
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Joined: June 10th, 2010, 6:22 am
Country: United States
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Re: Langmuir probe chara with Model 6487

Post by Dale C » September 17th, 2014, 6:43 am

There is a nice write up and diagram at this link about the Langmuir probe.
Please look at Figure 3.
Maybe this will help?

http://newton.physics.uiowa.edu/~rvogel ... obe_v4.pdf

venuanand
Posts: 6
Joined: May 12th, 2014, 10:50 pm
Country: India

Re: Langmuir probe chara with Model 6487

Post by venuanand » September 18th, 2014, 4:28 am

Thank you Dale.
I have another question. I am using a RF High voltage source (10kHz), to generate the plasma. So the probe - up an appreciable voltage (50 Vpeak). Is there and inbuilt blocking filter(inductor) in 6487 which prevents external signals from entering the instrument or Can I use the meter directly? Where do I get these details?

Dale C
Keithley Applications
Keithley Applications
Posts: 2849
Joined: June 10th, 2010, 6:22 am
Country: United States
Contact:

Re: Langmuir probe chara with Model 6487

Post by Dale C » September 18th, 2014, 5:14 am

The filter in the Model 6487 is a digital filter. It only filters the measurements.
You would to create your own filter and connect it externally.

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