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| TPPT095 | Test of a Fast Ferrite Reactive Tuner for Control of Microphonics at the S-Dalinac | |
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Funding: DOE A fast ferrite inductive tuner assembly has been constructed for use at the 3 GHz superconducting S-Dalinac accelerator. This device was installed and tested at the S-Dalinac in April 2005. At a fixed accelerating field of 1.4 MV/m using a simple analog control loop the amplitude of the cavity peak-to-peak phase fluctuations with respect to the phase of the incident RF was reduced from 80 degrees to 10 degrees. The 50 Hz noise which dominated the open loop microphonics was reduced by more than 30 dB. The open loop response of the reactive tuner has also been characterized, yielding a tuning range of ?f greater than 300 Hz at a Qext of 1.5e7. The ferrite tuner was then relocated on the waveguide to a distance of (n+1/4)? from the input coupler. This allowed fast control of the coupling with range of Qext from 1.5 - 8e7. |
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| RPAE068 | Very Short Bunches in MIT-Bates South Hall Ring | 3768 |
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Funding: Department of Energy The study of ultra-short bunches in MIT SHR storage ring with very small momentum compactions is carried out. The ultra-short bunches are to greatly enhence the coherent radiation by many orders of magnitude. The ring lattice is resigned to reach very small momentum compaction factor down to 1·10-5 levels. The measurement is performed with the streak camera. The various associated issues are discussed. |
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| RPAE069 | Terahertz Coherent Synchrotron Radiation in the MIT-Bates South Hall Ring | 3783 |
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| We investigate the terahertz coherent synchrotron radiation (CSR) potential of the South Hall Ring (SHR) at MIT-Bates Linear Accelerator Center. The SHR is equipped with a unique single cavity, 2.856 GHz RF system. The high RF frequency is advantageous for producing short bunch length and for having higher bunch current threshold to generate stable CSR. Combining with other techniques such as external pulse stacking cavity, femtosecond laser slicing, the potential for generating ultra-stable, high power, broadband terahertz CSR is very attractive. Beam dynamics issues related to short bunch length operation, and may associated with the high frequency RF system, such as multi-bunch instability are concerned. They could affect bunch length, bunch intensity and beam stability. The SHR is ideal for experimental exploration of these problems. Results of initial test of low momentum compaction lattice and bunch length measurements are presented and compared to expectations. | ||
| FPAE031 | Polarized Electron Beams for Nuclear Physics at the MIT Bates Accelerator Center | |
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Funding: U.S. Department of Energy. The MIT Bates Accelerator Center is delivering highly polarized electron beams to its South Hall Ring for use in Nuclear Physics Experiments. Circulating electron currents in excess of 200 mA with polarization of 70% are scattered from a highly polarized, but very thin atomic beam source deuterium target. At the electron source a compact diode laser creates photoemission of quasi-CW mA pulses of polarized electrons at low duty factors from a strained GaAs photocathode. Refurbished RF transmitters provide power to the 2856 MHz linac, accelerating the beam to 850 MeV in two passes before injection into the South Hall Ring. In the ring a Siberian snake serves to maintain a high degree of longitudinal polarization at the BLAST scattering target. A Compton laser back-scattering polarimeter measures the electron beam polarization with a statistical acuracy of 6% every 15 minutes. |