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Hand Sanitizing Plasma Device

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LAN_403

Tetris

Sat Nov 12 2011, 03:49AM

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

Hm... if I see this in reality in air ports and stuff, I'll go all geek on everyone that uses it. Hee hee... that's awesome.

Xray

Sat Nov 12 2011, 04:34AM

Registered Member #3429 Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288

The major problem with almost all atmospheric pressure glow discharges is the fact that they produce that nasty gas called Ozone! That's probably the reason why you don't see those devices at airports and other public places.

Pinky's Brain

Sat Nov 12 2011, 09:57AM

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

Only if they use atmospheric gas, you can supply them with a gas flow without oxygen.

Proud Mary

Sat Nov 12 2011, 01:32PM

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

I've only got the abstract of this experiment, but it looks very interesting, and not too hard to replicate:

Atmospheric pressure glow discharge in air using a water electrode

XinPei Lu Laroussi, M.
Electr. & Comput. Eng. Dept., Old Dominion Univ., Norfolk, VA, USA

This paper appears in: Plasma Science, IEEE Transactions on
Issue Date: Apr 2005
Volume: 33 Issue: 2
On page(s): 272 - 273
ISSN: 0093-3813
Cited by: 15
INSPEC Accession Number: 8387409
Digital Object Identifier: 10.1109/TPS.2005.844946
Date of Current Version: 23 May 2005

Abstract

An atmospheric pressure glow discharge in air is generated between the surface of a water electrode and a metal electrode with a high alternating current (60 Hz) voltage (<20 kV). The gap distance between the two electrodes can be adjusted from 3 mm to a few centimeters. The diameter of the plasma column is in the 3-10 mm range. Photographs taken with a high-speed charge coupled device camera clearly show a cathode fall region, negative glow, positive column, and anode dark space; a structure consistent with that of a normal glow discharge. The initial breakdown process shows that the plasma ignites at the water surface and terminates at the metal electrode. The N2 rotational and vibrational temperatures were spectroscopically measured to be about 1800 and 2600 K, respectively.

Pinky's Brain

Sat Nov 12 2011, 02:29PM

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

What if you just took aluminium plates, anodized them, cut some plastic into strips and put them in between the plates to form air channels similar to the device in the original post, put a Royer ZVS on the two plates and pumped some gas through it ... would that work?

Proud Mary

Sat Nov 12 2011, 03:14PM

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

Pinky's Brain wrote ...

What if you just took aluminium plates, anodized them, cut some plastic into strips and put them in between the plates to form air channels similar to the device in the original post, put a Royer ZVS on the two plates and pumped some gas through it ... would that work?

I'm only a beginner here, and the more you read up about glow discharges the more you realise there is to learn.

Certainly, there have been experiments using aluminia for DBD, which don't look too difficult or expensive:

Atmospheric pressure glow discharge plasma in air at frequency 50 Hz

A A Garamoon and D M El-zeer
2009 Plasma Sources Sci. Technol. 18 045006

Homogeneous atmospheric pressure discharge using a dielectric barrier discharge in air at 50 Hz was investigated. Porous alumina ceramic sheets were used as a dielectric barrier. In this paper we compare the filamentary discharge initiated by using glass sheets as a dielectric and the glow discharge obtained by the porous alumina sheets as a dielectric.

Generally, the discharge in a dielectric barrier arrangement consists of a large number of filaments. Using porous alumina sheets Al2O3, an atmospheric pressure glow discharge (APGD) plasma has been obtained. This APGD discharge is characterized by a homogeneous profile of long lifetime (~5 ms) and the current is one pulse per half cycle of the power supply. The electrical measurements and the emission spectrum confirm that the discharge has been formed in the glow mode.

___________________________________________ ____________________

I recall that arrays of nanoholes form spontaneously during the electrolytic formation of aluminia on an aluminium plate, so this might act in the same way as the porous 'alumina ceramic sheets' used in the above report.

Pinky's Brain

Sat Nov 12 2011, 06:07PM

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

I guess the plastic separators wouldn't work, after they char a bit I don't see much discharge going through the gas any more, probably needs glass. Can aluminized glass be had cheap? You could etch interlocking combs on a single piece of aluminized glass with hydrochloric acid and then anodize the aluminum.

Proud Mary

Sat Nov 12 2011, 08:01PM

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

Pinky's Brain wrote ...

I guess the plastic separators wouldn't work, after they char a bit I don't see much discharge going through the gas any more, probably needs glass. Can aluminized glass be had cheap? You could etch interlocking combs on a single piece of aluminized glass with hydrochloric acid and then anodize the aluminum.

What strikes me about all these glow discharge (GD) in air-at-atmospheric-pressure experiments reported in the literature is how recent they are for experiments of such simplicity. You'd have thought it would all have been sorted out by Victorian scientists like Crookes. I suspect that once there was a general assumption that GDs could only be produced with RF at low pressures, that decades went by before that assumption was tested.

Air - atmospheric pressure - 50 Hz sounds to me like a convenient and inexpensive place to start!

Pinky's Brain

Sat Nov 12 2011, 08:32PM

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

You can put in a lot more energy at higher frequencies.

Xray

Sat Nov 12 2011, 08:33PM

Registered Member #3429 Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288

Proud Mary wrote ...

What strikes me about all these glow discharge (GD) in air-at-atmospheric-pressure experiments reported in the literature is how recent they are for experiments of such simplicity. You'd have thought it would all have been sorted out by Victorian scientists like Crookes.

I've been wondering about that too. It's almost the same as if modern-day amateur radio operators were to start experimenting with spark-gap transmitters again because someone figured out a different way to make a spark!

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