THE ACCELERATION OF PARTICLES BY COLLECTIVE FIELDS II
The possibility of using the collective field of a large number of electrons to effect the acceleration of protons to high energies in a compact accelerator--or to permit acceleration of heavier ions in a manner not critically dependent on the charge-to-mass ratio of these ions--has been noted in an earlier Comment. A most attractive conceptual form for such an accelerator is the electron ring accelerator (ERA) and in the present Comment they direct attention to the basic phenomena--insofar as they know them--that govern the design and operation of an ERA. Briefly, the ERA concept visualizes the use of a compact ring of relativistic electrons that circulate in a plane perpendicular to an external magnetic field. The ring is partially neutralized by ions held in the potential well of the electrons. The electric field of these ions and the magnetic attractive forces between the circulating electrons then together act to overcome the electrostatic repulsion of the electrons and make possible the achievement of a configuration that is self-stable in the absence of external focusing fields. Acceleration of the ring with its accompanying ions, in a direction perpendicular to the plane of the ring, can be achieved (at the expense of the azimuthal motion of the electrons) by the action of a spatially decreasing magnetic guide field or, alternatively, by means of rf or pulsed electric fields. In any case the ring must provide a sufficiently strong'holding field' to permit ions to remain with the ring and thereby be carried to high energy in a short distance. An electron ring of suitable quality for this purpose might be formed by compressing a rather large and reasonably intense (e.g., {approx} 100 A, circulating) ring in a pulsed magnetic field, thereby reducing its major and minor radii from R {approx} 20 cm and a {approx} 1 cm to, for example, R {approx} 3 cm and a {approx} 0.1 cm. A ring of this intensity (N{sub e} {approx} 2-3 x 10{sup 12} electrons) and final dimensions would produce a holding field of some tens of MV per meter. The group at the Joint Institute for Nuclear Research, Dubna--formerly led by Veksler-- has been the first in forming and compressing rings and in demonstrating the acceleration of ions by means of them. Major development programs, employing pulsed compressors, are in progress at Dubna, Berkeley, Karlsruhe, and Garching (Munich). Related work with static-field compression is under way the University of Maryland and elsewhere. The possibilities and problems raised by the electron-ring concept have been reviewed recently by Keefe, who also provides some details concerning the experimental program at the Lawrence Radiation Laboratory, Berkeley. The Soviet work has already demonstrated--to a certain degree--the validity of the basic ERA concept, but, if an ERA device is to be useful, it is necessary to achieve rings of high quality; that is, rings of small dimensions and containing large numbers of electrons. Attention, therefore, must be directed to the fundamental limitations upon rings. After reviewing, in Section 1, the fundamental limits on rings, they shall discuss in Section 2 of the Comment the ultimate performance (as presently foreseen) of an ERA. Finally, in Section 3, they attempt briefly to summarize the present status of the ERA development.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- Accelerator& Fusion Research Division
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 937480
- Report Number(s):
- UCRL-20149; CNPPAV; TRN: US200819%%159
- Journal Information:
- Comments on Nuclear and Particle Physics, Journal Name: Comments on Nuclear and Particle Physics; ISSN 0010-2709
- Country of Publication:
- United States
- Language:
- English
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