This is about the last of the bell-jar-enclosed tests; soon he would shift gears.
You see a hood over the fusor; it is there because deuterium and tritium are isotopes, and technically are not desirable, they are, isotopes of hydrogen after all, and as such are very lightweight and the first thing hydrogen does when you let it out, is make a rapid bee line straight UP! If you need something to worry about, worry about that fusor; when operating it gives off lots of high energy in the way of neutrons and x-rays. Very dangerous.