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MOFAB4 |
Overview and SRF Requirements of the CiADS Project | |
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| Chinese initiative Accelerator Driven System started constructing in 2018. It consists a superconducting linac with 500 MeV and 5 mA; an LEB coolant fast reactor with 7.5 MW. The first beam coupling with reactor will be in 2024. The sc linac employed 5 families of superconducting resonators, two types of HWRs (β=0.1 and β=0.19), one type of double spokes (β=0.42) and two types of ellipticals (β=0.62 and β=0.82). The whole system will operate in 2 K. A space has been reserved for future upgrading to 1 GeV. As a demo of front-end of ADS, the CAFe (China ADS Front-end demo linac) has been developed and commissioned to verify the SRF techniques, high power CW beam and RAMI. 45 kW proton beam has been delivered to the dump and lasted more than 100 hours at the beginning of 2019. According to the operation experience, the challenge is the stability and performance of cavities under the heavy beam loading, some phenomenas have been observed. Up to now, the design of bulk Nb cavities have been finished and the prototype fabrication is on going. The techniques of Nb/Cu cavity and Nb3Sn are also developed in IMP for the future project of ADS. | ||
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Slides MOFAB4 [12.465 MB] | |
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| MOP073 | The Study of High Power Couplers for CIADS | 241 |
| SUSP007 | use link to see paper's listing under its alternate paper code | |
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| High power couplers with high operation reliability are needed for the superconducting cavities used in the Linac of CiADS project at IMP. This paper will report two works on high power coupler. The DC bias structure of the coupler was optimized to suppress the multipacting effect, where the series resistors were introduced to the wire of the DC bias to reduce the field propagating along the DC bias¿s wire. For the purpose of significantly decreasing the power needed to condition the coupler, we designed a new RF conditioning scheme, in which the coupler served as a standing wave resonator, and the positions of the crests and troughs of the wave were tunable. The details of the design mentioned above will be depicted. | ||
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Poster MOP073 [14.677 MB] | |
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP073 | |
| About • | paper received ※ 25 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019 | |
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| MOP085 | The Destructive Effects to the RF Coupler by the Plasma Discharge | 285 |
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| The low temperature RF plasma was proved an effec-tive method to clean the niobium surface and relieve the field emission effect for the SRF cavities. In the case of half-wave resonators, these cavities were usually powered via the fundamental coupler with the electric coupling. Thus, coupler antennas were fixed in the intense electric field region, and this region was where the plasma rou-tinely ignited. Therefore, the ceramic window of coupler taken the risk of breakdown under the sputtering of ions and heating loads that may be caused by the plasma drift and diffusion from the electric field region. In this paper, the plasma ignition for surface cleaning on the HWR cavity and its coupler was investigated, and the power transmission, temperature raising and vacuum degradation were tested to characterize the adverse impacts on the ceramic window. Finally, the solution was proposed to figure these issues. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP085 | |
| About • | paper received ※ 22 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019 | |
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| TUP075 | New Progress for Nb Sputtered 325 MHz QWR Cavities in IMP | 621 |
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| Comparing with bulk niobium cavities, the Nb/Cu cavities feature a much better stability at 4.5 K. Last year, two 325 MHz QWR copper cavities coated with biased DC diode sputterred Nb for CiADS has been accomplished at IMP. But vertical tests showed the cavities had low Q0 at 4 K. To solve the issue, a new coating system was designed and built. The sputtering target was redesigned and manufactured. The coating parameters were selected again and auxiliary heating was used to control the coating temperature in the process of sputtering. The power and Ar pressure during coating were also carefully selected. The paper covers resulting film characters, vertical tests with the evolution of the sputtering process, and improvements we made since last year. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP075 | |
| About • | paper received ※ 22 June 2019 paper accepted ※ 14 August 2019 issue date ※ 14 August 2019 | |
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