• G.M. Kazakevich, M.A. Davidsaver, H.T. Edwards, R.P. Fliller, T.W. Koeth, A.H. Lumpkin, S. Nagaitsev, J. Ruan, R. Thurman-Keup
  Fermilab, Batavia
• Y.U. Jeong
  KAERI, Daejon
• V.V. Kubarev
  BINP SB RAS, Novosibirsk

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359.

Noninvasive bunch duration monitoring has a crucial importance for modern accelerators intended for short wavelength FEL’s, colliders and in some beam dynamics experiments. Monitoring of the bunch compression in the Emittance Exchange Experiment at the A0 Photoinjector was done using a parametric presentation of the bunch duration via Coherent Synchrotron Radiation (CSR) emitted in a dipole magnet and measured with a wide-band quasi-optical Schottky Barrier Detector (SBD). The monitoring resulted in a mapping of the quadrupole parameters allowing a determination of the region of highest compression of the bunch in the sub-picosecond range. The obtained data were compared with those measured using the streak camera. A description of the technique and the results of simulations and measurements are presented and discussed in this report.

• N. Solyak, V.P. Yakovlev
  Fermilab, Batavia
• J.L. Hirshfield, G.M. Kazakevich
  Omega-P, Inc., New Haven, Connecticut
• M.A. LaPointe
  Yale University, Physics Department, New Haven, CT

Funding: Sponsored in part by US Department of Energy, Office of High Energy Physics.

A preliminary design is presented for a two-cavity 7th harmonic multiplier, intended as a high-power RF source for use in experiments aimed at developing high-gradient structures for a future collider. The harmonic multiplier is to produce power in K-band using as an RF driver an XK-5 S-band klystron (2.856 GHz). The device is to be built with a TE111 rotating mode input cavity and interchangeable output cavities, a principal example of which is a TE711 mode cavity running at 19.992 GHz. Design of the harmonic multiplier is described that uses a 250 kV, 20 A injected laminar electron beam. With 10 MW of S-band drive power, 4.7 MW of 20-GHz output power is predicted. Details are described of the gun beam optics, beam dynamics in the RF system, and of the magnetic circuit. The theory of an azimuthally distributed coupler for the output cavity is presented, as well as the conceptual design of the entire RF circuit.