I am a glassblower, and I would like to trap smoke in a glass bubble, my hope is to create an infinitely lingering smoke inside.
Is this possible?
Any mixture of gases (or smoke particles suspended in air) becomes a uniform mix in minutes. So whatever sample you trap in a glass bubble will be featureless in probably less than a minute. It will be indistinguishable from a uniform stain of the glass itself
As Wutaz writes, smoke particles will likely start sticking to the surface. At best that will result in the appearance of frosted glass, chances are the particles sticking to each other will look like deposited soot.
Iodine vapor has a strong color.
But again, the mix of Iodine vapor and air will become a uniform mix in minutes, if not faster. Also, you can't contain the toxic Iodine vapor in the furnace. It's clearly too dangerous to try something like that in a shop for handcrafted glasswork.
Smoke is made up of particles, so eventually they will settle. When they settle, they will probably stick to the surface of the glass and become impossible to stir up into smoke again.
You might be able to do this with a vapor. Because vapors are in the gas phase, they will not settle unless chilled. Unfortunately, a vapor will dissipate over time, resulting in a consistent color inside the bubble and not the "smokey" appearance that I assume you want.
There might be a way to use two gasses that won't mix, but even if that worked they would likely cause health problems if the bubble cracked open.