1. As for a more quiet SC, most of the noise comes from the cooling fan. Not sure how much more expensive the unit cost will go up trying to engineer and use a cooling system that is as effective in cooling yet quiet.
There's not much one can do to stop the resonate frequency you hear on some frequencies other than to avoid those frequencies, which would defeat the purpose.
You could take the SC and tube and put it in an adjacent room. If you can get the tube within 5 feet of where you sleep, it will have very decent efficacy still -- even through the wall.
Even if you were 10 feet away, it would afford better efficacy than avoiding it altogether.
Not the same as near field, but works good.
I do all my plasma applications at 5 feet from recipients, and have one who is affected by the output even at 40 feet away or so through 4 walls. You can tell the drop off in effectiveness at that range, but still impressive.
2. Another consideration, I have an air purifier which runs at night in the bedroom. It muffles all sounds inc the plasma. Sleep is much improved.
To help the plasma light flickering, wear a mask or hang it from a chair that sits just below the mattress edge. I also put my back to the plasma tube so it is not flashing in my eyes.
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