| Paper | Title | Page |
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| MOPLT066 | Induction Accelerating Cavity for a Circular Ring Accelerator | 704 |
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This paper reports details of an induction accelerating cavity employed for induction synchrotron POP experiments [*] using the KEK 12GeV PS. This cavity is the first induction cavity in the history of accelerator that is used in a circular ring. We focus our attention on crucial aspects distinguished from well-know properties of RF cavity. The single cavity is capable of generating an acceleration voltage of 2.5kV with a pulse width of 250ns, which is operated at a repetition rate in the range of 667kHz - 882kHz. The cavity is driven by its own pulse modulator through a 25m long transmission cable of 125W, the end of which is connected with a matching resistance so as to minimize reflection in a wide range of frequency. Accelerating field characteristics are discussed and matching features of the cavity as a one-to-one transformer are presented. A longitudinal and transverse coupling impedance have been measured using a net-work analyzer.
* K.Takayama et al., 'POP Experiments of the Induction Synchrotron' in this conference |
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| TUPLT078 | Study of Impedances and Instabilities in J-PARC | 1336 |
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| J-PARC consists of two high intensity proton rings with energies of 3 GeV and 50 GeV. Longitudinal impedances and instabilities, which are caused by beam chamber, cavities, kicker magnets and others, are mainly discussed in this paper. | ||
| WEPLT109 | Simulation of Ep Instability for a Coasting Proton Beam in Circular Accelerators | 2104 |
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| ep instability is discussed for a coasting beam operation of J-PARC 50 GeV Main Ring. Our previous study (PAC2003) was focussed only ionization electron. We now take into account electrons created at the chamber wall due to proton loss and secondary emission with higher yield than ionization. | ||
| WEPLT110 | Specific Beam Dynamics in Super-bunch Acceleration | 2107 |
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| Proof-of-principle experiments on the induction synchrotron concept using the KEK 12-GeV PS makes progress, in which RF bunches and a super-bunch will be accelerated with a long step voltage generated in the induction accelerating gaps. In order to give a guide for super-bunch acceleration, the beam stabilities against a droop and a fluctuation of the accelerating voltage have been examined by using a simulation. The droop voltage gives an additional focusing or defocusing force in the longitudinal direction, which leads the mismatching beyond the transition energy. Furthermore, the extremely slow fluctuation of the accelerating voltage causes a lowest-order resonance near the transition. These induce a serious emittance blow-up in the longitudinal, so that the compensating manners will be presented. Moreover, the other issues such as head-tail instability and intra beam scattering will be discussed. | ||
| THPLT074 | The Beam Loss Monitor System of the J-parc LINAC, 3 GEV RCS and 50 GEV MR | 2664 |
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| The high intensity beam accelerator complex itself requires the significant progress of design study and hardware R&D. Operational beam intensity should be limited by the beam loss and activation level of the equipment. Once the beam loss exceeds a criterion at outer environment, beam intensity has to be decreased to prevent the further activation. In order to investigate loss mechanism and suppress the beam loss, a beam loss monitor system have been developed for the J-PARC linac, 3 GeV RCS and 50GeV MR. The system will be essential component for beam commissioning, tuning and machine protection in high intensity beam accelerators. The loss monitor system is composed of scintillator, argon-methane/3He gas filled proportional counter and air filled coaxial cable ionization chamber, which detect g-ray, neutron and charged particles induced by lost particle. It is necessary to measure wide dynamic range of loss intensity for various beam energies. To prevent the activation and heat load by intense beam loss, fast time response of loss signals is required. In this paper, construction and application of loss monitor system are described in detail. Preliminary result of demonstration in the KEK-PS and calibration with cobalt 60 g-ray radiation source are also discussed. |