Plasma Pencil / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

Plasma Pencil

1 2 next

Move Thread

LAN_403

AleSeg

Tue Feb 14 2012, 03:15AM

Registered Member #2727 Joined: Tue Mar 09 2010, 02:39PM
Location: Montevideo - Uruguay
Posts: 33

Hi.
Is it possible to do a "plasma pencil" at home ? What do you think?
I think it's easier than a lot of works done before in this place.
Article In Wikipedia
Youtube video

Bye

jpsmith123

Tue Feb 14 2012, 03:35PM

Registered Member #1321 Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843

Hello AleSeq,

I think it's possible to make it at home, although you might need some machining work done and some experience working with RF/microwaves may be helpful.

I've seen several "plasma pencil" type devices that are said to operate at atmospheric pressure, but IIRC, they all needed to use at least some argon or helium gas mixed with air. So my main question is: does anyone have a successful design for a device that operates using just air at atmospheric pressure? If so, I would be interested in making one myself.

I looked at the Adtec web site, but unfortunately their site does not seem to have any information on the design and construction of their plasma torch (as demonstrated on the you tube video you've linked to for example).
Maybe they've got some patents you could examine. I usually try to look for patents at this place:

Let me know if you find any more info.

Ash Small

Tue Feb 14 2012, 04:50PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

jpsmith123 wrote ...

.
I looked at the Adtec web site, but unfortunately their site does not seem to have any information on the design and construction of their plasma torch (as demonstrated on the you tube video you've linked to for example).
Maybe they've got some patents you could examine. I usually try to look for patents at this place:

Let me know if you find any more info.

The wikipedia link above mentions a paper on the subject. I tried googling it, and found several others. Unfortunately, all the links I found were 'subscription only'. Maybe someone could sign up for a 'free trial' and download three of them and post details (or maybe someone here has a relevant subscription already, and could maybe enlighten the rest of us?)

EDIT: it appears to be a capacitatively coupled plasma, at a frequency in the kH, but with nanosecond pulses, from what I was able to read on the subject. It also mentions that helium is the gas of choice. (I was able to read the first page of one article)

Pinky's Brain

Tue Feb 14 2012, 06:04PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837

Ozone production is probably the reason why air isn't used in medical applications, also it's possible that ion species die out faster in air.

That said simply blowing air through a tube with electrodes on both sides, and insulation to make sure there are no external arcs, with a high AC voltage between them should generate plasma species (this is Double Barrier Discharge).

jpsmith123

Tue Feb 14 2012, 07:29PM

Registered Member #1321 Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843

I found a patent for the so-called "plasma pencil". I didn't have time to read it yet, but just skimming through it, it looks very simple.

Proud Mary

Tue Feb 14 2012, 07:37PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Absence of ozone production (as suggested by Pinky above) and room-temperature plasma temperature are the reasons given for choosing helium given in this letter:

Appl. Phys. Lett. 87, 113902 (2005)
Room-temperature atmospheric pressure plasma plume for biomedical applications
M. Laroussi and X. Lu

As low-temperature nonequilibrium plasmas come to play an increasing role in biomedical applications, reliable and user-friendly sources need to be developed. These plasma sources have to meet stringent requirements such as low temperature (at or near room temperature), no risk of arcing, operation at atmospheric pressure, preferably hand-held operation, low concentration of ozone generation, etc. In this letter, we present a device that meets exactly such requirements. This device is capable of generating a cold plasma plume several centimeters in length. It exhibits low power requirements as shown by its current-voltage characteristics. Using helium as a carrier gas, very little ozone is generated and the gas temperature, as measured by emission spectroscopy, remains at room temperature even after hours of operations. The plasma plume can be touched by bare hands and can be directed manually by a user to come in contact with delicate objects and materials including skin and dental gum without causing any heating or painful sensation.

Tetris

Tue Feb 14 2012, 08:10PM

Registered Member #4016 Joined: Thu Jul 21 2011, 01:52AM
Location: Gainesville, FL
Posts: 660

I thought plasma was extremely hot?

Pinky's Brain

Tue Feb 14 2012, 09:38PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837

Equilibrium plasmas are hot. Non equilibrium plasmas can be cold, aka non thermal plasmas.

Ash Small

Tue Feb 14 2012, 10:14PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I imagine this is why it uses nanosecond power pulses at kH frequency, which accelerate the electrons much more than the ions, thus giving high electron temperatures while the ions remain 'cold'.

The ions account for the vast majority of the mass, so the overall temperature rise is negligible, but I'm only guessing here.

Pinky's Brain

Tue Feb 14 2012, 11:45PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837

Microdischarges from a barrier discharge will do the same thing (because you can just use a normal AC voltage it is one of the easiest way of creating non thermal plasmas). Maybe they use pulses because a sine wave will put a little more thermal energy into the gas from dissipation? Or alternatively, it could just be a patent issue.

1 2 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob