Title : "A 13.56 MHz multicusp ion source for gaseous ion-beam production"

Researcher : Boonyawan D., Suanpoot P. and Vilaithong T.

Office of Researcher : PHYSICS


A 10cm x 9cm cylindrical radio-frequency (RF) driven multicusp ion source has been developed for producing high-current ion beams from gases. An inductively coupled 13.56 MHz RF plasma is produced in the presence of 20 rows of Sm-Co5 magnets which from a longitudinal line-cusp field configuration. The field design was generated using the computer program MAGNUS. By using a 0.35 Tesla magnet, the 100 eV electrons were confined in the source chamber. The RF antenna coil, coated with a thin layer of hard flexible glass to prevent electrical leakage and contamination, has power inlets into the source chamber. A 10:1 turns-ratio matching transformer was used in order to match the 50 W output impedance of the RF generator to the impedance of the plasma load. A test run has been performed with 0-500 W of RF power. The source parameters were measured with a Langmuir probe, a mass analyzer and a Faraday cup. For oxygen at 3 mtorr and power set at 500 W, the ion-current density is 36 mAcm-2, representing an ion density of 1.5 x 1011cm-2. The value for nitrogen operating at the same pressure is 34 mAcm-2and, for argon and helium at 10 mtorr source pressure, it is 29 and 27 mAcm-2, respectively. ã 1999 Elsevier Science S.A. All rights reserved.

Published in : Surface and Coating Technology 112, 1999, 314-317