IPAC2011 - List of Authors (Hirshfield, J.L.)

Paper	Title	Page
TUPC060	A Multi-mode RF Photocathode Gun	1135
	S.V. Kuzikov, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia J.L. Hirshfield Yale University, Physics Department, New Haven, CT, USA Y. Jiang Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA V. Vogel DESY, Hamburg, Germany
	A photocathode injection gun based on standard emittance compensating techniques and driven by several (N ≥ 2) harmonically related RF sources is considered. Multi-harmonic excitation can provide high-quality flatness in time of the field at the cathode when a bunch is being injected. This allows one to obtain ≥1 nC, 20-40 ps electron bunches with preservation of low emittance. Another advantage is a reduction of Ohmic losses and the required input RF power (for a given cathode field). Preliminary calculations show that input power in a three-mode cavity (0.65 GHz, 1.3 GHz, 2.6 GHz) is nearly half the power needed to feed a single mode with the same cathode field. A further appealing property is the predicted increase of breakdown threshold due to a reduction of surface exposure time to high fields in a symmetric cavity, and due to the so-called anode-cathode effect in a longitudinally asymmetric cavity. These properties may help one to reach bunch energies as high as 3-5 MeV after the first half cell.

THPC169	Short-Period RF Undulator for a Nanometer SASE Source	3293
	S.V. Kuzikov, M.E. Plotkin, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia J.L. Hirshfield Yale University, Physics Department, New Haven, CT, USA T.C. Marshall, G.V. Sotnikov Omega-P, Inc., New Haven, Connecticut, USA
	Funding: Sponsored in part by US Department of Energy, Office of High Energy Physics. A room-temperature RF undulator to produce ~1 nm wavelength radiation using a relatively low energy electron beam (0.5 GeV) is considered. The design features include an effective undulator period of 0.45 cm, an undulator parameter of K = 0.4, an effective field length of 50 cm. These parameters could be be realized using a multi-MW RF power amplifier to drive the undulator (e.g., the 34 GHz pulsed magnicon at Yale or a 30 GHz gyroklystron at IAP) with microsecond pulse duration. Two undulator designs were considered that avoid problems with a co-propagating wave: a dual-mode cylindrical cavity [TE01 (counter propagating) - TE02 (co-propagating)] with an off-axis electron beam; and a traveling HE11 mode resonant ring with an on-axis beam.

Paper

Title

Page

A Multi-mode RF Photocathode Gun

1135

S.V. Kuzikov, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia
J.L. Hirshfield
Yale University, Physics Department, New Haven, CT, USA
Y. Jiang
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
V. Vogel
DESY, Hamburg, Germany

A photocathode injection gun based on standard emittance compensating techniques and driven by several (N ≥ 2) harmonically related RF sources is considered. Multi-harmonic excitation can provide high-quality flatness in time of the field at the cathode when a bunch is being injected. This allows one to obtain ≥1 nC, 20-40 ps electron bunches with preservation of low emittance. Another advantage is a reduction of Ohmic losses and the required input RF power (for a given cathode field). Preliminary calculations show that input power in a three-mode cavity (0.65 GHz, 1.3 GHz, 2.6 GHz) is nearly half the power needed to feed a single mode with the same cathode field. A further appealing property is the predicted increase of breakdown threshold due to a reduction of surface exposure time to high fields in a symmetric cavity, and due to the so-called anode-cathode effect in a longitudinally asymmetric cavity. These properties may help one to reach bunch energies as high as 3-5 MeV after the first half cell.

THPC169

Short-Period RF Undulator for a Nanometer SASE Source

3293

S.V. Kuzikov, M.E. Plotkin, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia
J.L. Hirshfield
Yale University, Physics Department, New Haven, CT, USA
T.C. Marshall, G.V. Sotnikov
Omega-P, Inc., New Haven, Connecticut, USA

Funding: Sponsored in part by US Department of Energy, Office of High Energy Physics.
A room-temperature RF undulator to produce ~1 nm wavelength radiation using a relatively low energy electron beam (0.5 GeV) is considered. The design features include an effective undulator period of 0.45 cm, an undulator parameter of K = 0.4, an effective field length of 50 cm. These parameters could be be realized using a multi-MW RF power amplifier to drive the undulator (e.g., the 34 GHz pulsed magnicon at Yale or a 30 GHz gyroklystron at IAP) with microsecond pulse duration. Two undulator designs were considered that avoid problems with a co-propagating wave: a dual-mode cylindrical cavity [TE01 (counter propagating) - TE02 (co-propagating)] with an off-axis electron beam; and a traveling HE11 mode resonant ring with an on-axis beam.