High-Voltage switch controlled by LASER pulse


by pierebean
Tags: high voltage, high-voltage, laser, switch, trigger
pierebean
pierebean is offline
#1
Dec20-12, 12:43 AM
P: 8
Hello,

I wish to switch ON and OFF a high-voltage (that generates a high electric field) using a ultra-fast laser as a trigger.

Basically I have a flow of charged particles that I want to quickly deflect using an E-field. The timing must be correct and controlled by a LASER.

Does anyone know some way to achieve this scheme?

I know there are some pretty fast pulsed laser (picosecond? nanosecond?) can these frequencies "tranduce" a high voltage? Is there an intrinsic upper limit in term of frequency for the High-voltage switch?

Help will be much appreciated.
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Bobbywhy
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#2
Dec20-12, 03:34 AM
PF Gold
P: 1,852
pierebean, Your project sounds interesting. Surely some members here will be ready and willing to assist you with making it function. Will you please clearly describe your apparatus with more detail? This will help others who wish to contribute suggestions towards its realization.

Modern lasers can emit ultra short pulses, and with some techniques even femtosecond pulses may be developed. Your post title mentioned there was some high voltage switch that would be controlled by the laser. That appears to be a viable proposal.

1. Do you have a high voltage source? What voltage is it?
2. Do you need to turn on and also turn off the source with the laser?
3. What means “can these frequencies “transduce” a high voltage?” Are you proposing to generate some high voltage with the laser pulse?
4. What does “intrinsic upper limit in term of frequency for the HV switch” mean?

Just for your information, you aren’t the first to do this:
A STUDY OF PICOSECOND, HIGH-VOLTAGE PHOTOCONDUCTIVE SWITCHING USING ELECTROOPTIC DIAGNOSTICS AND COMPUTER-AIDED ANALYSIS
by
Lawrence Eric Kingsley
Submitted in Partial Fulfillment of the Requirements for the Degree
DOCTOR OF PHILOSOPHY
Abstract
This dissertation documents advances in the field of ultrafast, high-voltage, semiconductor photoconductive switching. New developments in experimental diagnostics and theoretical device simulation are presented. The output waveform of a laser-activated silicon photoconductive switch in a coaxial circuit was measured for bias voltages up to 20 kV. The switch was activated with a -150 ps laser pulse.
http://www.lle.rochester.edu/media/p..../Kingsley.pdf
++++++++++++++++++++++++++++
Laser-triggered high-voltage plasma switching with diffractive optics
www.opticsinfobase.org › ... › Volume 40 › Issue 16
+++++++++++++++++++++++++++++++++++++
Cheers,
Bobbywhy
pierebean
pierebean is offline
#3
Dec20-12, 04:47 AM
P: 8
Thank you Bobbywhy for your prompt response,

At the moment the apparatus is at an early stage. Before continuing further, I just want to how if it was feasible and preferential commercially available or even better "cheaply makeable".

I have a vacuum chamber with an electron source. On the other end of my chamber I have an electron detector. When I apply the high-voltage, the electrons flow along the chamber to my detector. I wish to prevent them to reach the detector at a certain time. This time need to be at the same frequency of the LASER beat.

For instance, if the LASER beat at 1 kHz. Then the detector will received an electron stream of 1kHz. I cannot use a mechanical shutter because the frequency is too low.

I read about femtosecond laser used in chemistry for pump&probe techniques. Although the pulse is short, I am not sure of the minimum usual beating frequency. Is it GHz THz ?

Here are some more information:

1) I do have a home-made (not by me) high-voltage source. I wish to work between 1kV up to 10kV but the less than 5kV is fine.
2) Perhaps it is not necessary to turn off and on the voltage. A simple modulation would be enough to deflect the electron beam enough so it could not reach the detector.
3) No, I meant to ask if it was possible to modulate or trigger the high-voltage using the Laser as a reference frequency.
4) I meant to ask if there was a physical upper limit (for the frequency) above which an electric field could not be turned ON and OFF. For instance, a don't think I could modulate my electron flux at say 1e14 Hz. I was just wondering what was the physical highest frequency I could achieve in theory.

Anyway, I'll have a look at the dissertation. Thank you so much for that and the article. It seems that my Google searchs were not powerful enough. It is an art after all!

Qapla'

berkeman
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#4
Dec20-12, 05:49 PM
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P: 39,611

High-Voltage switch controlled by LASER pulse


What is your high voltage source? HV power sources don't generally turn on and off very quickly. You can generate HV pulses in the 10kHz-100kHz range using a flyback topology, and you could even vary the frequency of the pulses a bit, but that doesn't sound like what you want.

Using a laser beam or a fiberoptic system to act as a trigger should be no problem. You just need a fast detector, like a PIN photodiode with good reverse bias and a current-to-voltage converter stage to give you a control signal.


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