Production of a large‐diameter uniform plasma by electron cyclotron resonance heating with a small‐diameter Lisitano coil

A large‐diameter uniform plasma is produced by electron cyclotron resonance heating with a slotted Lisitano coil of 9 cm in diameter by locating the resonance apart from the Lisitano coil. Although the plasma production with a Lisitano coil has been performed extensively by placing the resonance near the Lisitano coil, the influence of the resonance location has not received as much attention. When the resonance is located further than 8 cm from the Lisitano coil, the uniform plasma of ∼40 cm in diameter at densities of ∼1.2×1011 cm−3 is produced over the vacuum chamber with an inner radius of 46 cm. The microwave is propagated in the whole space between the resonance and the Lisitano coil, and spatial electric‐field distributions of the microwave play an important role on forming the radially uniform plasma.