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Eppley, K.

Paper Title Page
TPAT043 The MICHELLE 2D/3D ES PIC Code: Advances and Applications
 
  • J.J. Petillo, N.J. Dionne, K. Eppley, J. N. P. Panagos, X. Z. Zhai
    SAIC, Burlington, Massachusetts
  • L. C. Chernyakova, J.F. DeFord, B. H. Held
    STAR, Inc., Mequon, Wisconsin
  • B. Levush
    NRL, Washington, DC
  • E.M. Nelson
    LANL, Los Alamos, New Mexico
 
  Funding: Office of Naval Research, Naval Research Laboratory.

MICHELLE is a new 2D/3D steady-state and time-domain particle-in-cell (PIC) code* that employs electrostatic and now magnetostatic finite-element field solvers. The code has been used to design and analyze a wide variety of devices that includes multistage depressed collectors, gridded guns, multibeam guns, annular-beam guns, sheet-beam guns, beam-transport sections, and ion thrusters. Latest additions to the MICHELLE/Voyager tool are as follows: 1) a prototype 3D self magnetic field solver using the curl-curl finite-element formulation for the magnetic vector potential, employing edge basis functions and accumulating current with MICHELLE's new unstructured grid particle tracker, 2) the electrostatic field solver now accommodates dielectric media, 3) periodic boundary conditions are now functional on all grids, not just structured grids, 4) the addition of a global optimization module to the user interface where both electrical parameters (such as electrode voltages)can be optimized, and 5) adaptive mesh refinement improvements. Applications illustrating these latest additions will be presented, including a relativistic sheet beam gun, a relativistic MIG gun, and a depressed collector optimization example.

*John Petillo, et al., IEEE Trans. Plasma Sci., vol. 30, no. 3, June 2002, pp. 1238-1264.

 
WPAT031 Design and Operation of a High Power L-Band Multiple Beam Klystron 2170
 
  • A. Balkcum, H.P. Bohlen, M. Cattelino, L. Cox, M. Cusick, S. Forrest, F. Friedlander, A. Staprans, E.L. Wright, L. Zitelli
    CPI, Palo Alto, California
  • K. Eppley
    SAIC, Burlington, Massachusetts
 
  A 1.3 GHz, 10 MW, higher-order-mode multiple beam klystron (MBK) has been developed for the TESLA program. The relative advantages of such a device are many-fold. Multiple beams generate higher beam currents and thereby require much lower operating voltages which allows for the use of smaller, less expensive modulators. A lower perveance per cathode can also be used which leads to higher operating efficiencies. Higher-order-mode cavities allow for the use of much larger cathodes which leads to lower cathode current density loadings and subsequently longer cathode lifetimes. This requires that the cathodes be located far off the geometric axis of the device. The compromise is an increase in the complexity of the magnetic focusing circuit required to transport the off-axis electron beams. Such a device has been successfully built and tested. Excellent beam transmission has been achieved (99.5% DC and 98% at RF saturation). A peak power of 10 MW with 150 kW of average power and 60% efficiency, 49 dB gain have also been measured. The achieved low cathode loading of 2.1 A/cm2 corresponds to an expected cathode life of over 140,000 operational hours.