Aside from the gun-type device, there's the implosion-type device.
What is implosion?
Usually, explosions occur outward, but implosion is different; it compresses inward.
An implosion-type device uses the energy of explosives to rapidly compress sub-critical nuclear materials into a very small volume to reach supercritical status.
It's like having thousands of students on a playground simultaneously pushing towards the center, eventually gathering in a few square meters; their density becomes incredible. With nuclear materials, it's atoms reaching a frightening density, greatly exceeding critical mass.
Thus, the utilization rate of nuclear material is higher, and the power is greater, although the technical difficulty increases.
The most critical issue is how to synchronize the compression of numerous nuclear materials. For example, how can a thousand people in a playground reach the center simultaneously?
