Abstracts Brochure - CERN

TUPCH — Poster Session 27-Jun-06 16:00 - 18:00
High Power Coaxial FEM Based on Surface Photonic Band Gap Structures
High frequency (26.5GHz to 40GHz), high
power (tens of MW) microwave sources are
required for cavity testing and conditioning
applications in accelerators such as CLIC.
I.V. Konoplev, A.W. Cross, W. He, P. MacInnes, A. Phelps, C.W.
Robertson, K. Ronald, C.G. Whyte (USTRAT/SUPA)
The first study of microwave radiation from a co-axial Free-Electron Maser (FEM) based on a two-mirror cavity
formed by a 2D Surface Photonic Band Gap (SPBG) structure (input mirror 10.4cm) and 1D SPBG structure (output
mirror 10cm) is presented. The electron beam source consisted of a magnetically insulated plasma flare emission
carbon cathode. Application of a 450kV voltage pulse of duration ∼250ns across the cathode and grounded anode
resulted in the production of a 7.0cm diameter annular electron beam of current ∼1500A. The output radiation power
from the FEM was measured using a Ka-band horn with 60dB of attenuation in front of a microwave detector located
at a distance of 1.5m from the output window. By integrating the microwave power measured at the detector over the
radiation pattern a total power of 50 (±10) MW corresponding to an efficiency of ∼9% was calculated. The location
of the operating frequency was found to lie between 35GHz and 39GHz, which agrees with theoretically predicted
frequency of 37.2GHz.
Design and Simulation of a Cusp Gun for Gyro-amplifier Application in High Frequency
RF Accelerators
Gyro-amplifiers have potential as the high
frequency RF drivers for particle accelerators.
They require relativistic electron beams
with low velocity spread and with a high
fraction of the electron energy associated
D.H. Rowlands, A.W. Cross, W. He, A. Phelps, E.G. Rafferty, C.W.
Robertson, K. Ronald, J. Thomson, C.G. Whyte, A.R. Young (US-
TRAT/SUPA)
with the cyclotron motion. For harmonic operation and mode control an axis-encircling beam is desirable. The
passage of an electron beam through a non-adiabatic magnetic field reversal (cusp) converts part of the electron
beam’s axial velocity into axis-encircling transverse velocity. A cusp-based electron beam forming system, yielding
a 10MW, 150kV, 70A axis-encircling beam will be presented. This cusp gun is being designed as the electron beam
source for a microwave gyro-amplifier that is relevant for high frequency accelerator applications. The latest results
from numerical simulations and experiments will be presented and compared.
Installation and Commissioning of the High Power, IOT Based, 300 KW CW Amplifier at
Diamond
The Diamond Light Source requires up to 900
kW of RF power at 500 MHz to make up for
radiation losses. This power will be supplied
from three high power amplifiers provided
by Thales. Each amplifier is capable of deliv-
M. Jensen, M. Maddock, S.A. Pande, S. Rains, A. F. Rankin, D. Spink,
A.V. Watkins (Diamond) J. Alex, M. Mueller (Thomson Broadcast
& Multimedia AG)
ering 300 kW through the combination of four 80 kW broadcast type IOTs. This paper provides an overview of the
measurements of the key parameters following installation at Diamond, as well as the operating experience during
initial storage ring beam commissioning.
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