This paper introduces the principle and design of a new integration cell for a long pulse integrator with ul- tra-low drift. Based on principles of zero compensation and chopper

the integration cell was designed and developed

and it will be used to constitute an integrator

to complete integration of a long duration of pulse up to one thousand second on the super-conducting tokama facility. Compared with the traditional analog integrator

this integration cell has ultra-low drift with a typical absolute drift value of 16.7mV

when the time constant is 9.78ms. Secondly

its nonlinear error caused by the capacity leakage was also well diminished.