# How to mantain plasma current in a tokamak?

I know that a toroidal plasma current is an essential feature on tokamaks as it creates the poloidal magnetic field essential to avoid separation between negative and positive charges.

The current is created inducing a magnetic field with an increasing current applied to a central coil which in turn induces a current in the plasma.

My question is how to keep the current for long experiments (such as ITER project)? One can go from a minimum value on the central coil (even better maximum negative value) to a maximum value, but that is the limitation. What are the options there?

cheers

• Hi Kyril. You are asking a question that researchers have been asking for 50+ years. I am not sure you will get many answers unless you greatly narrow it down. Jun 17 '21 at 12:50

• Transformer: causing a $$dI/dt$$, it induces a current. Of course, the transformer at some point gets too expensive and physically impossible to operate since it cannot keep changing current ad infinitum.