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"plasma candle" Could this be a good source of UV?


Fandyus

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"In this video I show you a plasma candle made from an ultra high frequency solid state tesla coil (HFSSTC). I talk about why it was tripping the breakers in my house and show you how hot these plasma candles actually are. I talk about why the color of the "flame" is white vs blue or violet."

 

Spoiler: He says the "candle" is about 11000K.

 

Now, I'm no physicist or an electrical engineer, so I apologize if this is me just being stupid, but wouldn't something this hot emit a lot of UV? Or is this different?

 

I very much recommend this channel by the way, a lot of though provoking videos and experiments, sometimes it's a little clickbaity, sometimes it's a little oversimplified, but overall really good channel.

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Such a device will almost certainly emit some UV. However, it may not be a very intense source compared with an arc lamp or similar device.. The exact wavelengths emitted will depend on the composition of the surrounding air and the amount of power provided.
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Andy Perrin

At 11000K, the blackbody peak would be about 260nm. So quite a lot of UV if it were a blackbody. Gases emit a discrete line spectrum from individual electronic jumps between energy levels, and plasmas can have a mix of individual jumps and free electrons causing blackbody-like behavior, but I bet the peak wavelengths will be in the same ballpark. Air does absorb in the 200nm range, but we've found on the forum from David's experiments that at short distances it doesn't absorb that strongly.

 

It doesn't seem very practical, though. I wouldn't want to have anything that hot anywhere near my apartment.

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One thing I have contemplated is a cold plasma source and passing iodine vapor through it to get a 208nm line.

Remember plasma by its nature is not hot. Its just the ionization or deionized state of matter. Just like not all solids are cold.

Most great UV lines come from Mercury. But that is quite dangerous. Iodine has a 208nm peak.

 

You can make a cold plasma like this:

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Having done my PhD on cold plasma systems, I always find it amusing when people go "and look how perfectly safe it is, I can stick my finger in it". Yes, it is cold. However there is a lot of UV in there, and the ionised particles are still highly energetic and can cause damage tissue, or at the very least oxidise the lipids in the outer layers of the skin resulting in skin barrier damage.

 

David, interesting about the iodine giving a 208nm line. I didn't know that.

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Having done my PhD on cold plasma systems, I always find it amusing when people go "and look how perfectly safe it is, I can stick my finger in it". Yes, it is cold. However there is a lot of UV in there, and the ionised particles are still highly energetic and can cause damage tissue, or at the very least oxidise the lipids in the outer layers of the skin resulting in skin barrier damage.

 

David, interesting about the iodine giving a 208nm line. I didn't know that.

 

Ok my brain is fuzzy again. Its 183nm and 206nm for a vaporized iodine lamp. I remember trying to figure out the best deep UV source that were cheap and saw that people were making "home made" in the lab that is quartz iodine bulbs to cheaply get those lines.

 

I would like to buy one, hoping that they would have been more common after all the 222nm paper discussions.

 

I am now seeing papers discussing the 150nm to 210nm advantage of iodine. Maybe Covid will give me a cheap deep uv light source. The Examer lamps are stupidly expensive.

 

This iodine lamp seems promising:

 

https://www.researchgate.net/publication/257830518_A_High-Power_Low-Pressure_Iodine_Lamp_Pumped_by_Glow_Discharge

 

One day maybe I could build one.

 

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