| Paper | Title | Page |
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| MOPMR035 | Bunch Length Measurements using a Transverse Deflecting Cavity on VELA | 323 |
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| The VELA facility at Daresbury Laboratory in the UK includes a 5 MeV/c 2.5 cell S-band photoinjector gun. This gun operates in the "blow-out" regime with a sub-200 fs length drive laser: the resulting bunch length is determined by space-charge effects. We present measurements made with an S-band transverse deflecting cavity to characterise the bunch length as a function of charge, and as a function of the gun operating phase. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR035 | |
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| MOPMR038 | Design and Simulation Studies of the Novel Beam Arrival Monitor Pickup at Daresbury Laboratory | 334 |
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| We present the novel beam arrival monitor pickup design currently under construction at Daresbury Laboratory, Warrington, UK. The pickup consists of four flat electrodes in a transverse gap. CST Particle Studio simulations have been undertaken for the new pickup design as well as a pickup design from DESY, which is used as a reference for comparison. Simulation results have highlighted two advantages of the new pickup design over the DESY design; the signal bandwidth is 25 GHz, which is half that of the DESY design and the response slope is a factor of 1.6 greater. We discuss optimisation studies of the design parameters in order to maximise the response slope for bandwidths up to 50 GHz and present the final design of the pickup. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR038 | |
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| TUPOW040 | UH-FLUX: Compact, Energy Efficient Superconducting Asymmetric Energy Recovery LINAC for Ultra-high Fluxes of X-ray and THz Radiation | 1847 |
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Funding: This work was supported (in part) by The Leverhulme Trust through the International Network Grant IN-2015-012. The conventional ERLs have limited peak beam current because increasing the beam charge and repetition rate leads to appearance of the beam break-up instabilities. At this stage the highest current, from the SRF ERL, is around 300 mA. A single turn (the beam will be transported through the accelerating section, interaction point and deceleration section of the AERL only once) Asymmetric Energy Recovery LINAC (AERL) is proposed. The RF cells in different sections of the cavity are tuned in such a way that only operating mode is uniform inside all of the cells. The AERL will drive the electron beams with typical energies of 10 - 30 MeV and peak currents above 1 A, enabling the generation of high flux UV/X-rays and high power coherent THz radiation. We aim to build a copper prototype of the RF cavity for a compact AERL to study its EM properties. The final goal is to build AERL based on the superconducting RF cavity. Preliminary design for AERL's cavity has been developed and will be presented. The results of numerical and analytical models and the next steps toward the AERL operation will also be discussed. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW040 | |
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| TUPOY025 | ProBE - Proton Boosting Extension for Imaging and Therapy | 1963 |
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| Conventional proton cyclotrons are practically limited by relativistic effects to energies around 250 MeV, sufficient to conduct proton therapy of adults but not for full-body proton tomography. We present an adaptation of the cyclinac scheme for proton imaging, in which a c.250 MeV cyclotron used for treatment feeds a linac that delivers a lower imaging current at up to 350 MeV. Our ProBE cavity design envisages a gradient sufficient to obtain 100 MeV acceleration in 3 metres after focusing is included, suitable for inclusion in the layouts of existing proton therapy centres such as the UK centre under construction at Christie Hospital. In this paper, we present the results of design studies on the linac optics and RF cavity parameters. We detail particle transmission studies and tracking simulation studies. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY025 | |
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| WEPMB058 | LHC Crab Cavity Coupler Test Boxes | 2248 |
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| The LHC double quarter wave (DQW) crab cavities have two different types of Higher Order Mode (HOM) couplers in addition to a fundamental power coupler (FPC). The FPC requires conditioning, so to achieve this we have designed a radio-frequency (RF) quarter wave resonator to provide high transmission between two opposing FPCs. For the HOM couplers we must ensure that the stop-band filter is positioned at the cavity frequency and that peak transmission occurs at the same frequencies as the strongest HOMs. We have designed two test boxes which preserve the cavity spectral response in order to test the couplers. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB058 | |
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| WEPMB060 | Modifications to the Pump Out Box to Lower the Qext of Diamond SCRF Cavities | 2251 |
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| Diamond's CESR-B cavities are iris coupled and have fixed Qext. For reliability, the cavities are operated at lower voltages. This results in the optimum condition for beam loading being satisfied at a much lower power typically about 100 kW. For operation at 300 mA with two cavities, the RF power needed per system exceeds 200 kW. Consequently, the cavities need to be operated under-coupled. To lower the Qext and move the optimum operating point nearer to 200kW, 3 stub tuners are used in the waveguide feed line. The difference in the height of the coupling waveguide on cavity and that of the vacuum side waveguide on the window assembly results in a step transition which affects the Qext. The present window/step location results in Qext higher than that without the window. The Qext can be lowered by re-locating the RF window or by shifting the step change in the waveguide cross-section from its present location. This needs modification to the Pump Out box. The pros and cons of the proposed modification to the pump out box in terms of standing waves and multipacting characteristics studied with CST Studio are discussed in this paper. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB060 | |
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| WEPMY025 | iMPACT, Undulator-Based Multi-Bunch Plasma Accelerator | 2609 |
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Funding: This work is supported by the Cockcroft Institute Core Grant and STFC. The accelerating gradient measured in laser or electron driven wakefield accelerators can be in the range of 10-100GV/m, which is 2-3 orders of magnitude larger than can be achieved by conventional RF-based particle accelerators. However, the beam quality preservation is still an important problem to be tackled to ensure the practicality of this technology. In this global picture, the main goals of this study are planning and coordinating a physics program, the so-called iMPACT, that addresses issues such as emittance growth mechanisms in the transverse and longitudinal planes through scattering from the plasma particles, minimisation of the energy spread and maximising the energy gain while benchmarking the milestones. In this paper, a summary and planning of the project is introduced and initial multi-bunch simulations were presented. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY025 | |
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| THPMB056 | Witness Beam Production with an RF Gun and a Travelling Wave Booster Linac for AWAKE Experiment at CERN | 3378 |
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Funding: This work is supported by the Cockcroft Institute Core Grant and STFC. AWAKE is a unique experiment that aims to demonstrate the proton driven plasma wakefield acceleration. In this experiment, proton bunches from the SPS accelerator will be injected into a 10m long pre-formed plasma section to form wakefields of hundreds MV/m to several GV/m. A second beam, e.g., the witness beam, will be injected after the protons in an appropriate phase to gain energy from the wakefields. A photo-injector will be utilised to deliver this second beam. It consists of an S-band RF gun followed by a meter long accelerating travelling wave structure (ATS). The RF gun was recuperated from existing PHIN photo-injector. A 3D RF design of the ATS was done by using the CST code and the field maps produced were used to characterise the electron beam dynamics under space charge effect by using the PARMELA code. The impact of the mechanical errors on the beam dynamics were investigated. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB056 | |
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| THPOW017 | VELA Photoinjector Cavity RF Investigations | 3968 |
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| One of two ALPHA-X photocathode gun cavities, designed and fabricated at the Laboratoire de l'Accélérateur Linéaire, has been in operation on the VELA electron accelerator at Daresbury Laboratory since first beam in April 2013. In this time the maximum beam momentum recorded is 5.06 MeV/c. An investigation of the cavity has been performed with the aim of reconciling the expected momentum of over 6 MeV/c with the measured momentum. RF and beam simulation results are presented along with low power RF measurements of the cavity. One source of momentum loss, the flatness of the cathode face, is identified and rectified. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW017 | |
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