And your right, they were so shocked and surprised by its power that they never dared try to test one again.
"Tsar Bomba" ("King of Bombs"): The World's Largest Bomb
Time: 30 October 1961 Location: Parachute retarded airburst, 4000 m altitude Over Novaya Zemlya Island test range (in the Arctic Sea) Yield: 50 Megatons
Shown here (NOT SHOWN) in the Russian Atomic Weapon Museum, the "Tsar Bomba" was the largest nuclear weapon ever constructed or detonated. This three stage weapon was actually a 100 megaton bomb design, but the uranium fusion tamper of the teritiary (and probably secondary) stage(s) was replaced by one made of lead to eliminate fast fission by the fusion neutrons. The result was also the cleanest weapon ever tested with 97% of the energy coming from fusion reactions.
This weapon was developed in a remarkably short time. On 10 July 1961 Nikita Khruschev met with Sakharov, then the senior weapon designer, and directed him to develop a 100 megaton bomb. This device had to be ready for a test series due to begin in September so that the series would create maximum political impact (a bomb this size is virtually useless militarily). Sakharov returned to Arzamas-16, and selcted a design team consisting of Victor Adamskii, Yuri Babaev, Yuri Trunev, and Yuri Smirnov (who later oversaw the transformation of this design into a fielded weapon). The bomb was tested only 14 weeks after the initiation of its design.
The effect of this bomb at full yield on global fallout would have been tremendous. It would have increased the world's total fission fallout since the invention of the atomic bomb by 25%. The fabrication of the massive parachute disrupted the Soviet nylon hosiery industry. It weighed 27 metric tons. Some were actually stockpiled.
The bomb was air dropped by a Tu-95 strategic bomber piloted by A. E. Durnovtsev (made Hero of the Soviet Union).