Performance of a modified Calutron-Bernas ion source

Conference · Mon Jan 01 04:00:00 EST 1990 · Review of Scientific Instruments; (USA)

OSTI ID:7003469

Pratap, R; Lal, K B; Salvi, V P ^[1]

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1. Physics Department, Bombay University, Bombay-98, India (IN)

The Calutron-Bernas ion source has been modified for high-dose ion implantation ({gt}10{sup 16} ions/cm{sup 2}). The modified ion source has stable arc, uniformly bright illumination, and dense plasma. It consists of a hairpin-shaped tungsten (W) filament as a hot cathode at one end, and a disk-type graphite anode at the other end about 8 cm away; both the electrodes are fitted in an arc discharge chamber made of graphite only. The anode potential of 150--200 V and filament current of about 60 A initiates a stable bright arc. A magnetic field (0.1--0.5 kG) along the cathode-anode axis enhances the electron ionizing efficiency, helps in collimating the electrons, and contributes also in the plasma confinement near the aperture. The operational life of {ital W} filament (1.2 mm diam) in an ambient of oxygen or nitrogen at pressure 10{sup {minus}3}--10{sup {minus}4} Torr varies from 25 to 35 h. Further, a needle valve or an in-built minioven is used, respectively, when the feed material is a gas/liquid or a solid charge. The gas/vapors is/are admitted at a proper location into the arc chamber so as to be conducive for the generation of high-density plasma. One rectangular face of the arc chamber (graphite box) is provided with an aperture (8 cm{times}0.2 cm) for lateral extraction of ions. For most elements, the extracted ion beam that is subsequently accelerated through a mass analyzing 60{degree} magnetic sector is quite intense at the target; the nitrogen ion-beam current has been achieved up to 60 {mu}A/cm{sup 2}. Consequently, high-dose implantation ({approx gt}10{sup 17} ions/cm{sup 2}) of singly charged 30-keV ions has been carried out for surface modification of materials.

• OSTI ID: 7003469
• Report Number(s): CONF-890703--
• Conference Information: Journal Name: Review of Scientific Instruments; (USA) Journal Volume: 61:1
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
430301* -- Particle Accelerators-- Ion Sources
ANODES
BEAM CURRENTS
BEAMS
CARBON
CATHODES
CONFINEMENT
CONTROL
CURRENTS
DESIGN
ELECTRODES
ELEMENTAL MINERALS
ELEMENTS
FILAMENTS
GRAPHITE
ION BEAMS
ION IMPLANTATION
ION SOURCES
MAGNETIC FIELDS
METALS
MINERALS
NITROGEN
NONMETALS
OXYGEN
PLASMA CONFINEMENT
PRESSURE CONTROL
TRANSITION ELEMENTS
TUNGSTEN