Diagram of the clover leaf trap. The cloverleaf trap consists of 12 magnetic coils. Two coils, which we call the "curvature" coils, are arranged in helmholtz configuration, producing a magnetic field which is provides axial confinement. We call these coils "curvature" coils because the field they produce has zero gradient (no first derivative) near the center of the trap.

Eight other coils (four on each side) called the "gradient" or "cloverleaf" coils, provide radial confinement. The shape of these coils give our cloverleaf trap its name.

The last two coils, called the "anti-bias" coils serve to lower the bias field at the center of the trap. These coils are larger than the curvature coils, so they produce a much more uniform field than the curvature coils. This allows us to counter the bias field created by the curvature coils without making a large compromise on their confining power.

---