How to make 2d char run inside a circle

Hi all, I need to let a 2Dcharacter run inside a circle I have tryed a lot of ways but finally I did not find a solution.

My approach was to ray cast the ground and then to apply a force by considering the normal of the point hitten. something like:

 Ray2D ray = new Ray2D (gameObject.transform.position, empty.transform.position);
         RaycastHit2D hit; 
         Physics2D.Raycast (ray, out hit);
 
         gameObject.GetComponent<Rigidbody2D>().AddForce(hit.normal* (-100));

(where the "empty" game object is placed under the feets of the character). I have correctly deactivated the gravity from the rigidbody2d but it does not work correcly and i do not understand why.

ps: the idea of the normals is driven by the fact that the circle is not a real circle but a set of short segments