25 July 1989 Production Of Intense Negative Ion Beams In Strong Magnetic Field Ion Sources: Vitex And Ringatron
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Abstract
The Oak Ridge National Laboratory (ORNL) Fusion Energy Division (FED) negative ion development program has concentrated on the use of Penning discharges in a strong magnetic field. Extraction from the discharge has taken place both perpendicular and parallel to the confining magnetic field. The former has received by far the greater development effort. The ion source produced is called VITEX for Volume Ionization with Transverse EXtraction. Attempts to extract parallel to themagnetic field have recently begun and the ion source principle has been labeled Ringatron. A plan view of a Penning discharge as used in VITEX is shown in Fig. 1. An elevation view is shown in Fig. 2. A thin sheet plasma of thickness D(1) is formed with energetic electrons of density on the order of 1013 cm-3. A secondary cold plasma of thickness D(2) is formed in the region immediately surrounding the energetic electron sheet due to diffusion. Negative ions formed in the discharge may be extracted transverse to the magnetic field with suitable electrodes as shown in Fig. 2. Probe studies coupled with geometrical variations on the thickness of D(1) and D(2) indicate that the two chamber model of Hiskesl is a valid production mechanism. A variation to the extraction geometry of VITEX is to take the sheet plasma of energetic electrons and wrap it around into a cylinderical annulus as shown in Fig. 3. Thus, excited molecular neutrals are fed into the core of the discharge from the entire annulus. The core is similar to the region D(2) of the VITEX geometry. Negative ions produced in the core are free to drift along the magnetic field to the extraction electrodes at which point they are accelerated parallel to the magnetic field. This source is called Ringatron due to the ring or annular nature of the discharge.
© (1989) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
W. L. Stirling, W. L. Stirling, M. A. Akerman, M. A. Akerman, G. C. Barber, G. C. Barber, W. R. Becraft, W. R. Becraft, W. K. Dagenhart, W. K. Dagenhart, A. Fadnek, A. Fadnek, D. E. Schechter, D. E. Schechter, T. D. Steckler, T. D. Steckler, C. C. Tsai, C. C. Tsai, J. H. Whealton, J. H. Whealton, } "Production Of Intense Negative Ion Beams In Strong Magnetic Field Ion Sources: Vitex And Ringatron", Proc. SPIE 1061, Microwave and Particle Beam Sources and Directed Energy Concepts, (25 July 1989); doi: 10.1117/12.951855; https://doi.org/10.1117/12.951855
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