A high-current ion source requires a high-density plasma source to provide sufficient ions to be accelerated. For a continuous high-power ion source, a new concept ion source using a helicon plasma source has been developed. A compact high-density helicon plasma is generated with very high-power efficiency, and ion beams are extracted from the plasma source. With various plasma parameters, extracted ion-beam characteristics are studied in a helicon ion source for the first time. Plasma parameters, especially plasma density, are shown to be strongly correlated with the extracted beam characteristics. (C) 2000 American Institute of Physics. [S0034-6748(00)55402-1].