Methods and apparatus for controlling a magnetic field in a plasma chamber are provided herein. In some embodiments, a process chamber liner may include a cylindrical body, an inner electromagnetic cosine-theta (cos θ) coil ring including a first plurality of inner coils embedded in the body and configured to generate a magnetic field in a first direction, and an outer electromagnetic cosine-theta (cos θ) coil ring including a second plurality of outer coils embedded in the body and configured to generate a magnetic field in a second direction orthogonal to the first direction, wherein the outer electromagnetic cos θ coil ring is disposed concentrically about the inner electromagnetic cos θ coil ring.