| Paper |
Title |
Page |
| TUP005 |
Design of an RFQ-Based Neutron Source for Cargo Container Interrogation
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253 |
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- J. W. Staples, M. D. Hoff, J. W. Kwan, D. Li, B. A. Ludewigt, A. Ratti, S. P. Virostek, R. Wells
LBNL, Berkeley, California
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An RFQ-based neutron generator system is described that generates pulsed neutrons for the active screening of sea-land cargo containers for the detection of shielded special nuclear materials (SNM). A microwave-driven deuteron source is coupled to an electrostatic LEBT that injects a 40 mA D+-beam into a 6 MeV, 5.1 meter-long 200 MHz RFQ. The RFQ has a unique beam dynamics design and is capable of operating at duty factors of 5 to10% accelerating a D+ time-averaged current of up to 1.5 mA at 5% duty factor, including species and transmission loss. The beam is transported through a specially-designed thin-window into a 2-atmosphere deuterium gas target. A high-frequency dipole magnet is used to scan the beam over the long dimension of the 5 by 40 cm target window. The source will be capable of delivering a neutron flux of 2·107 n/(cm2·s) to the center of a cargo container. Details of the ion source, LEBT, RFQ beam dynamics and gas target design are presented.
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| THP007 |
Timing Distribution in Accelerators via Stabilized Optical Fiber Links
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577 |
| |
- J. M. Byrd, L. R. Doolittle, A. Ratti, J. W. Staples, R. B. Wilcox
LBNL, Berkeley, California
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We present progress on fiber-optic based systems for highly stable distribution of timing signals for accelerators. This system has application for linac-based sources of ultrafast radiation which require sub-100 fsec synchronization or for very large accelerators such as the linear collider. The system is based on optical fiber links that are stabilized with an optical interferometer with RF and timing signals distributed as modulations on the optical carrier. We present measurements of the stability of this link over distances of several hundred meters and discuss issues for testing the link over 10 km.
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| THP008 |
Detailed Modeling of the SNS RFQ Structure with CST Microwave Studio
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580 |
| |
- D. Li, J. W. Staples, S. P. Virostek
LBNL, Berkeley, California
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We report detailed RF modeling on the SNS RFQ structure using CST Microwave Studio code. Due to the complexity of the RFQ structure, a three-dimensional model with large mesh ratio is required to adequately model the necessary details of the structure. Old 3-D codes are not capable of giving accurate predictions of resonant frequency and fields, or for including mode stabilizers and terminations. A physical prototype is needed to verify resonant frequency and field profile, including mode stabilizers and end terminations, which is expensive and time consuming. Taking advantage of CST Microwave Studio’s new Perfect Boundary Approximation (PBA) technique, we constructed a 3-dimensional computational model based on the as-built SNS RFQ dimensions with pi-mode stabilizers, end cutbacks and tuners and simulated it in the frequency domain using the CST Eigenvalue Solver. Simulation results accurately predicted the resonant frequency and field distributions. We are applying the simulation technique to the design of another RFQ.
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