I noticed that a magnetic field will bend the streamers. Weird. There's some asymmetry and some DC ion current going on there. (Try a neo rare-earth magnet.)

Even better, you can create a Faraday HPG-style PLASMA MOTOR. Lower a long stack of neo magnets into the mug. (Maybe stick a bit of bubblepack in there first, so dropped magnets don't shatter the glass.) The orange streamers will rotate at a few thousand RPM, creating a uniform glow in the mug. Move the magnets slowly and you can find a spot where the rotation slows and becomes visible to human eyes. Now turn the magnet stack upside-down and create counter-rotation. Mentioned by Tesla in his 1892 lecture before the Royal Society.

Be careful running it from 24 volts, there is no current limiting to speak of and the 2SD882's Vcbo and Vceo are only 40 and 30 volts respectively.

To be completely safe you should do it by cautiously increasing the voltage while measuring the current drawn and also observing the waveforms at the transistor. Do the maths as well to ensure you aren't exceeding the ratings of the device, it is only specified for 1 watt without a heatsink and the one supplied isn't very big, plus its locked up inside the box.

Blowing up the transistor wouldn't be too bad, it can be replaced easily, but the transformer would be tough to rewind.

Hi there - I got my Plasma Mug from Can You Imagine - looks identical and is really fun to have on my desk. I just touch the glass with my finger and the plasma runs all around the glass! I haven't tried it with external power yet! Maybe about 24VDC would be really interesting? Bill in Milton-Freewater