Session 8: Low and Intermediate Energy Accelerators and ... - CERN

field in the beam passing region to act as a steerer. In
order to keep sufficient beam-focusing force, the iron
piece shape of the gradient corrector has been
optimized to increase the field gradient in the gap,
changing with excitation currents of the coils.
Type of presentation requested: Poster
Classification: [T12] Beam Injection/Extraction and
Transport
98-1303 - Progress in Ideal High-intensity
Unbunched Beams in Alternating Gradient
Focusing Systems
Ronak Bhatt, Chiping Chen, Enrique Henestroza, Jing
Zhou (MIT/PSFC, Cambridge, Massachusetts)
A persistent challenge in high-intensity accelerator
design is the optimization of matching conditions
between a beam injector and a focusing system in order
to minimize non-laminar flows, envelope oscillations,
emittance growth, and halo production. It has been
shown [*] that the fluid motion of a thin space-charge
dominated beam propagating through a linear magnetic
focusing channel consisting of any combination of
uniform or periodic solenoidal fields and alternating
gradient quadrupole fields can be solved by a general
class of corkscrewing elliptic beam equilibria. The
present work extends this discussion to asymmetric
PPM focusing and derives conditions under which a
uniform density elliptical beam can be matched to such
a focusing channel by considering the fluid equilibrium
in the paraxial limit. Methods of constructing such a
beam are also discussed, with particular attention
devoted to analytic electrode design for Pierce-type
gun diodes of elliptical cross-section. Several
applications are discussed, including heavy-ion fusion
and a high-efficiency ribbon beam microwave
amplifier for accelerator applications.
This work was performed under the auspices of the U.S
Department of Energy and the Air Force Office of
Scientific Research
* C. Chen, R. Pakter, R. Davidson, "Ideal Matching of
Heavy Ion Beams," Nucl. Inst. And Methods, A 464
(2001) p. 518-523
Type of presentation requested: Poster
Classification: [T12] Beam Injection/Extraction and
Transport
99-1335 - Upgrade of the Kiloampere Electron Gun
with Secondary Emission
Sergiy Cherenshchykov (NSC/KIPT, Kharkov)
The Secondary Emission Magnetron Injection Gun
(SEMIG) is a novel universal electron source with a
cold cathode. It may be used for charge particle
accelerators in injectors and power electron vacuum
devices (RF and pulse).The SEMIG may have higher
current density and lifetime much longer (up to
100,000 hours) than conventional thermionic guns.
High power SEMIG with voltage up 1000 kV and
current nearly 1 kA was calculated designed and
manufactured. The gun was tested microsecond
operating modes. The cathode testing permitted to obtain
beam pulse with amplitude up to 1.2 kA at voltage of 400
kV in magnetic field of 0.3 T. There were obtained beam
traces on the copper plate. Traces had the form of rings with
diameter of 125 mm and width of 5 mm. The secondary
emission nature of the beam current up to 1.2 kA was
established. The identification was held basing on
considered features of the exciting and on the maintenance
of the secondary emission current. The large amount of
criterion gives the high validity of the identification.
Type of presentation requested: Poster
Classification: [T12] Beam Injection/Extraction and
Transport