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Title: Variable energy constant current accelerator structure

A variable energy, constant current ion beam accelerator structure is disclosed comprising an ion source capable of providing the desired ions, a pre-accelerator for establishing an initial energy level, a matching/pumping module having means for focusing means for maintaining the beam current, and at least one main accelerator module for continuing beam focus, with means capable of variably imparting acceleration to the beam so that a constant beam output current is maintained independent of the variable output energy. In a preferred embodiment, quadrupole electrodes are provided in both the matching/pumping module and the one or more accelerator modules, and are formed using four opposing cylinder electrodes which extend parallel to the beam axis and are spaced around the beam at 90.degree. intervals with opposing electrodes maintained at the same potential. Adjacent cylinder electrodes of the quadrupole structure are maintained at different potentials to thereby reshape the cross section of the charged particle beam to an ellipse in cross section at the mid point along each quadrupole electrode unit in the accelerator modules. The beam is maintained in focus by alternating the major axis of the ellipse along the x and y axis respectively at adjacent quadrupoles. In another embodiment, electrostaticmore » ring electrodes may be utilized instead of the quadrupole electrodes.« less
Authors:
 [1]
  1. (Berkeley, CA)
Publication Date:
OSTI Identifier:
867316
Report Number(s):
US 4912421
DOE Contract Number:
AC03-76SF00098
Resource Type:
Patent
Research Org:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA
Country of Publication:
United States
Language:
English
Subject:
variable; energy; constant; current; accelerator; structure; variable; energy; constant; current; beam; accelerator; structure; disclosed; comprising; source; capable; providing; desired; pre-accelerator; establishing; initial; energy; level; matching; pumping; module; means; focusing; means; maintaining; beam; current; main; accelerator; module; continuing; beam; focus; means; capable; variably; imparting; acceleration; beam; constant; beam; output; current; maintained; independent; variable; output; energy; preferred; embodiment; quadrupole; electrodes; provided; matching; pumping; module; accelerator; modules; formed; opposing; cylinder; electrodes; extend; parallel; beam; axis; spaced; beam; 90; degree; intervals; opposing; electrodes; maintained; potential; adjacent; cylinder; electrodes; quadrupole; structure; maintained; potentials; reshape; section; charged; particle; beam; ellipse; section; mid; quadrupole; electrode; unit; accelerator; modules; beam; maintained; focus; alternating; major; axis; ellipse; axis; respectively; adjacent; quadrupoles; embodiment; electrostatic; electrodes; utilized; quadrupole; electrodes; beam output; accelerator module; accelerator module; accelerator module; beam current; constant current; constant current; disclosed comprising; output current; major axis; beam accelerator; energy level; particle beam; preferred embodiment; charged particle; beam axis; source capable; variable energy; variable energy; accelerator structure; accelerator structure; output energy; beam focus; accelerator modules; accelerator modules; means capable; focusing means; initial energy; extend parallel; variable output; constant beam /315/313/