Can lasers create visible plasma channels in air?

In summary, the conversation discusses the possibility of creating a visible plasma channel through the path of a high power laser. While lasers are typically invisible in clear air, it is believed that with enough power, the air could be ionized into plasma, creating a visible channel. This idea has been explored in research for anti-missile systems, but was ultimately dropped in favor of using a high-intensity laser to disrupt the missile. However, it is possible to create a visible laser spark or long plasma channels with the use of powerful lasers and long-focus lenses. Some examples of this have been observed with 50-J, 10 ns lasers pulses and very-high-power fs lasers pulses.
  • #1
kuartus4
25
0
I have a question. In an electric arc, the electric current going through the air makes a visible plasma arc as so:

http://upload.wikimedia.org/wikipedia/commons/7/7a/Electric_arc.jpg

My question is this: Could a high power laser create a visible plasma channel through its path. I ask because laser beams are invisible in clear air, but what if it was powerful enough to ionize the air into plasma? Would there be some type of visible laser channel?
 
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  • #2
hi there

As far as I am aware ... Lasers are NON-ionising radiation, so no ionising could occurlets se ewhat others have to say :)

Dave
 
  • #3
I believe they could IF the power absorbed by the channel of air is sufficiently high, as that would heat the air high enough to ionize it. I believe small particles present in the air may make this easier. But it's got to be a LOT of power in a small amount of time.
 
  • #4
Back in the 1980's there was some research on laser-steered charged particle beams for anti-missile systems. The notion was to use high-intensity beams to ionize a channel for the beam by the means Drakkith described. I think the concept was dropped when it was realized that a high-intensity laser could be more easily constructed that was by itself sufficient to disrupt a ballistic missile. A prototype airborne anti-missile laser was built and successfully tested (see "Airborne Laser Laboratory", "Airborne Laser Testbed", "Boeing YAL-1"). This program was canceled by the Obama administration.
 
  • #5
kuartus4 said:
Could a high power laser create a visible plasma channel through its path. I ask because laser beams are invisible in clear air, but what if it was powerful enough to ionize the air into plasma? Would there be some type of visible laser channel?

Powerfull laser beam of visible wavelength is visible in the air under day light. For example 532-nm laser beam with few millimeters in diameter can be visible at power of several watts. The main reason of its visibility is scattering on dust particles. But even in dust-free air there is some scattering as well.

Concerning plasma channels there is such phenomenon as laser breakdown of air. It takes place near focus of a focusing lens. There is an examle - . Here the laser spark is very short, but its length can be made much longer using powerful laser and long-focus lens. E.g. I'd observed about 2-m long lasers sparks with aid of 50-J, 10 ns lasers pulses.

Very long plasma channels can be produced using very-high-power fs lasers pulses. At this level of power self-focusing of the beam in air is obtained making the beam to be self-collimated. http://www.dmphotonics.com/fs_filamentation.htm
 
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1. What are plasma channels created by lasers?

Plasma channels are ionized gas channels that are created by intense laser beams passing through a neutral gas. The laser energy strips electrons from the gas atoms, creating a highly conductive plasma channel.

2. How are plasma channels formed by lasers used?

Plasma channels created by lasers have many applications, including guiding and focusing laser beams, accelerating particles, and creating extreme conditions for studying matter. They can also be used for laser-induced breakdown spectroscopy (LIBS) and laser-induced breakdown detection (LIBD) in analytical chemistry.

3. What are the advantages of using plasma channels by lasers?

Plasma channels created by lasers have several advantages, including the ability to guide high-power laser beams over long distances with minimal energy loss. They also have a high damage threshold, making them useful for high-power laser applications. Additionally, plasma channels allow for precise control and manipulation of the laser beam, making them useful for various scientific and industrial purposes.

4. Can plasma channels created by lasers be controlled?

Yes, plasma channels created by lasers can be controlled using various techniques such as adjusting the laser parameters, using external magnetic fields, or shaping the laser beam. These methods allow for precise control over the channel's size, shape, and direction, making them useful for different applications.

5. What are the challenges in creating and controlling plasma channels by lasers?

One of the main challenges in creating and controlling plasma channels by lasers is the precise manipulation of the laser beam. This requires advanced laser technology and precise control systems. Additionally, there may be issues with maintaining the stability and uniformity of the plasma channel, which can affect its performance in applications.

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