Brian Gormley, who is segregated because of "previous incidents" involving patients and staff, punched a ward manager six times in the head, at 2.15pm, on January 25.
When other staff rushed to assist, he also hit two trainee nursing associates, leaving them with bruising and lumps, said prosecutor Neil Hollett.
Jaimie Nelson, mitigating, said Gormley was transferred to Rampton from a prison where he had been "vulnerable", and used by other prisoners to carry out violence on their behalf.
But after his arrival at the hospital, he was attacked with a snooker cue, which resulted in brain damage and "extremely low" impulse control.
Despite this, said Mr Nelson, Gormley made good progress for a while, but his behaviour deteriorated, and he was now described as "unpredictable."
"He is well aware this isn't acceptable behaviour," Mr Nelson added.
Gormley, 36, admitted the assaults when he appeared via video-link, at Mansfield Magistrates Court, on Friday.
He was ordered to pay the ward manager £200 compensation, and £50 to each trainee.
You can read more of the latest cases from Mansfield here.