To run the plasma, I need to supply a pulse with width 20us repeating at 500Hz.
I would then like to turn this plasma “on” and “off” at a certain frequency, say 4 hz.
I thought I would be able to do this in burst:gated mode.
However, when I check the output by running in MultiInstrument mode with and oscilloscope, the output is really weird.
Firstly, when “on” the pulse frequency is super variable and not close to 500 hz. Secondly, when “off”, it outputs 2.5 V - whereas I want it to be 0 V. I couldn’t figure out how to fix this.
Screen shots below
Thanks
P.S This discussion board only allows me to attach one image, so I have chosen the oscilloscope, if you need more i’ll email you directly or something.
Hello @hwedwards ,
Thank you for contacting Liquid instruments! Just to make sure I understand your system, you want to produce a pulse train that has a frequency of 500 Hz, and then you want to turn it on and off at a rate of 4 Hz, correct? If that is the case, it’s easier to break it down into cycles/time. For example, you want a 500 Hz pulse (500 pulses / second) and you want that turned on and off 4 times per second (on 250 ms, off 250 ms, etc). That means when the system is ‘on’, there will be 125 pulses (500 pulses/s * 250 ms) and then the system will be ‘off’ for 250 ms, then 125 more pulses and so on. You can achieve this by using the burst mode in conjunction with a 2 Hz trigger signal.
Since the burst takes 250 ms to finish, you should only trigger at half of the repetition rate. For example, at time 0, 125 cycles will be outputted which takes 250 ms. This means that we don’t want to trigger for another 250 ms so we want to trigger the pulses every 500 ms or 2 Hz. I hope this was helpful!
