Ionization of Air with a Laser

  • Context: Undergrad 
  • Thread starter Thread starter mecheng2011
  • Start date Start date
  • Tags Tags
    Air Ionization Laser
Click For Summary

Discussion Overview

The discussion revolves around the ionization of air when a class 4 laser is fired into a small enclosure. Participants explore the conditions under which ionization might occur, the parameters of the laser being used, and the implications for a project involving imaging within the enclosure.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • Some participants suggest that lasers can ionize air if focused with sufficient energy, referencing Laser-induced breakdown spectroscopy.
  • One participant questions the necessity of proving that ionization cannot occur, asking for clarification on the specific conditions being considered.
  • Another participant emphasizes that the energy density of the laser beam is crucial for determining whether ionization will happen, noting their own experience with a different laser setup.
  • Alex provides specific details about the laser being used, including its emission wavelength, output energy per pulse, pulse duration, and frequency, indicating a belief that ionization is unlikely under these conditions.
  • Alex mentions finding a journal article suggesting that ionization is not a concern below a certain intensity threshold (1GW/cm²).

Areas of Agreement / Disagreement

Participants express differing views on the conditions necessary for ionization to occur, with some agreeing on the importance of energy density while others remain uncertain about the specific parameters that would lead to ionization in Alex's setup. The discussion does not reach a consensus on whether ionization will occur in Alex's specific case.

Contextual Notes

There are limitations regarding the assumptions made about laser parameters and the specific conditions under which ionization might occur. The discussion highlights the dependence on definitions of intensity and energy density, which remain unresolved.

Who May Find This Useful

This discussion may be useful for individuals interested in laser applications, ionization phenomena, and experimental setups involving high-energy lasers in confined spaces.

mecheng2011
Messages
6
Reaction score
0
Hi guys,

I am currently doing a project which involves firing a class 4 laser into a small enclosure (200mmx200mm) and onto a target, which is to emit IR. I am trying to theoretically prove that there will be no ionization of the air (i.e. turn the air into plasma) inside the enclosure.

So far, I have an incredibily unreliable source and little else. From my searches I have found little information, but it may be because I am unsure of what exactly I am looking for (I am from a Mechanical Engineering background). The source is this: http://www.panoptesv.com/SciFi/LaserDeathRay/Ionization.html

Does anyone know if this information is valid/credible? If so, I could really do with any links to any kind of publication (book, journal, etc) from which I can reference properly, I don't really know where to find this kind of information.

Many thanks for help you can provide.

Alex
 
Physics news on Phys.org
I don't know about death rays but lasers can be focused with enough energy to break down air. Look into Laser-induced breakdown spectroscopy.
 
mecheng2011 said:
Hi guys,

I am currently doing a project which involves firing a class 4 laser into a small enclosure (200mmx200mm) and onto a target, which is to emit IR. I am trying to theoretically prove that there will be no ionization of the air (i.e. turn the air into plasma) inside the enclosure.


Alex

Hi Alex;

There are certain parameters and conditions necessary for laser ionization to occur.

So I hope you don't mind me asking:
1.Why are you trying to "prove" that ionization CANNOT occur?
2.Are you trying to "prove" that it cannot occur only under your particular conditions?
3.What is the laser frequency?

...
 
Last edited:
Thanks for your help.

1.The reason is that there will be a camera looking inside the tool, and if there is ionisation this will flare the camera image.

2.Yes, I am only trying to prove that under my conditions it will not occur. If it will occur, then I will have to design the enclosure to be purged.

3.The laser details are:

Emission wavelength: 1064nm
Output Energy per Pulse: 160mJ
Pulse Duration: 17ns
Pulse Frequency: 1-20Hz (variable)

As this is for a unviersity project, I am pretty sure that it will not occur, but I want to be able to show I have considered that it could occur and can show references for any calculations I have used.

Thanks again

Alex
 
Will the laser beam come to a focus in the enclosure?

I have a 10 mJ/pulse laser at 250 nm, with pulse length of 10 ns. It will only cause air ionization when it comes to a focus (which is why that section of the beam path is in vacuum). So here, the energy "density" in a unit volume will be a factor.

Are you able to test this out first?

Zz.
 

Similar threads

Graduate Lasers can be used to ionize air....
  • · Replies 5 ·
Replies
5
Views
4K
Undergrad Can a circularly Polarized Laser impart momentum to air?
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Can surface plasmons be used to build GeV gamma-ray lasers?
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Photoluminescence Excitation (PLE) vs PL spectroscopy
  • · Replies 4 ·
Replies
4
Views
10K
Undergrad Air Breakdown With 980nm Laser: 1microsec/250mW
  • · Replies 10 ·
Replies
10
Views
2K
Undergrad Intersecting 2 continuous laser in thin air to create a dot
  • · Replies 4 ·
Replies
4
Views
2K
Graduate The coherence length is much longer than the manufacturer claims
  • · Replies 10 ·
Replies
10
Views
3K
Heat transfer in wing by anti-ice system using hot air in piccolo tube
  • · Replies 6 ·
Replies
6
Views
2K
Graduate Questionable research practices in Nuclear Fusion
  • · Replies 1 ·
Replies
1
Views
3K
Undergrad Defending the Earth from meteors using lasers
  • · Replies 44 ·
2
Replies
44
Views
6K