Plasma position and shape control method for thermonuclear device and device therefor

There are disposed a first measuring device having high accuracy for a short measurement time, a second measuring device having a not time dependent constant accuracy and a operation processing means for determining a control amount by weighing the measuring values for both of them. At the initial stage of the operation, the weight is increased for the signals of the first measuring device and the object is controlled mainly based on the signals. As the time elapses from the start of the operation, the control amount based on the measuring value of the second measuring device is increased, and the ratio of the control amount based on the measuring value of the first measuring device is decreased. When the object to be controlled changes, the weight on one of the measuring devices is provisionally increased in accordance with the change, thereby moderating the influence on the measuring device caused by the change. Control can be conducted always based on the most accurate measuring value and further, undesirable influences on the measuring device caused by time change for the control amount is moderated by the other of the measuring devices, thereby enabling to suppress lowering of the control accuracy. (N.H.)