Well let’s do some math and see.
By “disintegrate” I’m assuming that simply breaking them into small pieces doesn’t count, you don’t want any residue left after. This means at a minimum you need to break the bonds between the atoms in the body. This is called ionization and would turn the body into a plasma.
The ionization energy varies by element, but for both hydrogen and oxygen(the main elements in the body, as it’s mostly water) the ionization energy is roughly the same at ~12 eV (eV are electron volts, a unit of energy).
You would need to heat the body to a temperature such that 12 eV is the typical energy of a molecule or atom. Assuming a black body radiator, Temperature = Energy/ Boltzman constant. So 12 eV corresponds to a temperature of 140,000 Kelvin (which is also about 140,000 C or 250,000 F). That’s pretty hot!
Raising the temperature of a body to 140k K would understandably take a lot of heat or energy. It takes about 4000 Joules to raise temperature of 1 kg of water by 1 degree C. Assuming a 100 kg body that is pure water, getting to 140k C from room temperature (27 C) takes about 5.6E8 Joules. Fun fact, Wolfram Alpha tells me that’s about one third the energy in a typical lighting bolt. I should note I’ve assumed the energy goes to raising the temperature of water, but the body would quickly turn into steam before reaching the plasma phase. So there’s more energy needed for that phase change but we’ll neglect it.
I assume you want this to be instantaneous, and not you sitting there with a blowtorch slowly vaporizing a body bit by bit. In that case you need to consider how to couple the energy to hearing the body. You’d want some form of radiation that is highly penetrating, so it goes throughout the entire body all at once. But if the radiation passes through the body easily, then it can also escape and not deposit all its energy. There will be a lot of inefficiency in order to ensure the body is heated uniformly.
So you need much more radiation energy than my estimate. Let’s assume 1% efficiency for a rough estimate - this would mean the energy deposition throughout the body is very uniform, and it vaporizes all at once. Now you need 5E10 joules, which Wolfram alpha points out is about the energy release from fissioning 2/3 of a gram of uranium (foreshadowing!).
The amount of radiation energy we’re discussing would be difficult if not impossible to focus or direct, especially if you want the energy to be delivered in a fraction of a second (quick disintegration vs slow boiling). So if you create a source of energy with sufficient power, it will radiate in all directions. Only a small fraction will hit the body. I’ll assume a solid angle of 10% (90% misses the body). Now you need 5E11 Joules, or fission of 6 grams of uranium.
If you have a device that can fission 6 grams of uranium in a fraction of a second then congrats on becoming a nuclear armed state.
In summary, vaporizing a body would require placing it within the fireball of a nuclear detonation. While that is technically possible, I don’t think it fits the spirit of a “disintegration gun”.
It’s possible. It just requires insane amounts of energy. Like the center of a nuke kind of energy. I don’t think there’s any controled way of doing it with a hand held weapon.
Best we can do is a gory explosion.
Sure, a big enough explosion will vaporize anyone you want.
