Extraction of single-ion beams from helicon ion source in high plasma density operation mode: Experiment and simulation
- Institute of Applied Physics, National Academy of Sciences of the Ukraine, Sumy (Ukraine)
Tests of a high plasma density high-brightness helicon ion source for nuclear microscopy applications are underway. Experiments were performed with hydrogen, helium, and argon. Different extraction structures of the helicon rf ion source were investigated with an imposed external magnetic field. We present measurements of the extracted current as a function of the extraction voltage and rf power. The source has been diagnosed by a microwave interferometer. Plasma densities in the vicinity of the emission hole of up to 7.2x10{sup 12} cm{sup -3} (for argon), 1.6x10{sup 12} cm{sup -3} (for helium), and 6.0x10{sup 11} cm{sup -3} (for hydrogen) were obtained for working gas pressure of <5 mTorr and rf power <350 W (f{sub rf}=27.12 MHz). The ion current density was 80 mA/cm{sup 2} with high percentage of protons in the beam ({approx}80%). In the extraction structure, the cathode channel has a 3 mm length and a 0.6 mm diameter. The phase set degradation due to aberrations in the extraction structure of the helicon rf ion source was simulated for a fourth-order approximation in series expansion of the electrostatic potential and third-order approximation in series of the magnetic fields, by the matrizant method. The calculations were performed involving experimental data on ion energy spread, average ion energy, and plasma density of the helicon rf ion source with permanent magnets.
- OSTI ID:
- 20779083
- Journal Information:
- Review of Scientific Instruments, Vol. 77, Issue 3; Conference: 11. international conference on ion sources, Caen (France), 12-16 Sep 2005; Other Information: DOI: 10.1063/1.2147739; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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