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Need to release as a LASER beam in order to ionize a certain substance

  1. Aug 26, 2010 #1
    A few questions which i could not find complete answers online (for a physics noob). I'll try and break them down here:
    // Comment: as for a good noob, i know nothing of the real calculation. //

    How do i calculate the amount of energy i will need to release as a LASER beam in order to ionize a certain substance ( assuming it is transparent and LASER can go through it) ?

    Does the LASER frequency (Hz) has any meaning in this case or just the power (W)?

    Given a certain frequency X and a certain power Y, how many free electrons / ions will it create for a certain substance?

    How many free electrons / ions do you need to have in a certain volume in order for it to be conductive?

    And have many more but will be waiting for the answers to those so maybe i can conclude some of the answers for the following questions.

  2. jcsd
  3. Aug 26, 2010 #2
    Re: Ionization

    Hi Gab

    A transparent medium through which laser can propagate will have an absorption rate (no matter how small it is). This will tell you the energy absorbed by the medium when laser passes through it. (Just as we have Specific Absorption Rate (SAR) in case of microwaves). You can use it to determine the laser power required.

    Laser frequency determines the energy the of the photons as per the equation (E=hf) where f is the frequency. You will have to study the effect of radiation of particular frequency on the medium through which laser passes. Power refers to the intensity of the Laser Beam.

    You will have to study about the medium to answer the last 2 questions.

    Everybody: please make corrections to the above if required.
  4. Aug 26, 2010 #3
    Re: Ionization

    Hey Bejoynp,
    Thanks for the quick answer.
    Well, i thought it must have an absorption rate since it is a matter and the photons do collide with some atoms over there otherwise it won't be a matter but just a void.

    Tried looking at google but couldn't find a table with SARs for that. Do you have this kind of thing anywhere?

    what does 'h' means? Assuming 'f' is the [Hz] frequency and 'E' is the [N] energy (correct me if i'm wrong).

    Let's take for example total clear water as a substance. Just H2O. Ignore reflection and breaking. How do i find the water's SAR (which should be relatively hight to the density)? And if so, what is the formula to understand the correlation between the density of the matter and the amount of energy to the laser beam to ionize it?

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