Hi there, I have a question about the Teller–Ulam hydrogen bomb design. This will be a long post , but I hope someone can answer it for me. When the first bombs were created, uranium device was simple enough to to figure out. Two sub critical masses of u-235 joined at..... I think it was 3000 feet per second to create a critical mass. I think from what I read tungsten carbide was use as a neutron reflector to get the reaction going to achieve an explosion. Correct me if I am wrong. The second bomb they dropped was a plutonium bomb. This gets a little complicated. From what I have read / watched, the plutonium was in a hollow sphere, because p-239 will fizzle if brought to critical mass. They then took high explosives and compressed the the sphere of plutonium to critical mass. Not sure if a tamper was needed. (correct me if I am wrong but I think a tamper is a neutron reflector) Anyway the to designs worked, but along comes the hydrogen bomb. The way I think this works is as folllows: plutonium atom bomb goes off, which is very hot turning the polystyrene foam (basically styrofoam) into a plasma which in turn with the xrays given off sets the hydrogen fusion device to go off. So basically I am just wondering with the ICBM MIRVS, do they still use the implosion technique, or do they use a neutron generator to set off the plutonium device, and if so do they use a tamper. Thanks for taking a look at this. I am very tired and am going to go to bed now, but I hope someone can answer this. I cannot find any information in documentaries, or on google. Thank you.