Helicon high-density plasma sources: physics and applications

Helicon high-density (up to ~1013 cm−3) plasma sources using a radio frequency wave in the presence of a magnetic field under a low pressure are very promising for various application fields owing to the flexibility of external operational parameters. In addition, these sources have interesting inherent characteristics. Herein, the basic features of helicon wave plasmas including production mechanisms are briefly described, focusing on some similarities to other fields. Examples of specific helicon sources are also introduced. Then, an extensive variety of applications ranging from fundamental to practical applications, which are very influential for further development in each field, are introduced, emphasizing crucial points.