Purpose The accelerator-driven subcritical system(ADS)is the internationally recognized key technology of nuclear waste problem treatment,of which superconducting proton linac is an important part.With the support of ...Purpose The accelerator-driven subcritical system(ADS)is the internationally recognized key technology of nuclear waste problem treatment,of which superconducting proton linac is an important part.With the support of the strategic science and technology pilot project of the Chinese Academy of Sciences,the Institute of High Energy Physics of the Chinese Academy of Sciences took the lead in the research of 325 MHz superconducting proton linac,which is called ADS Injector I.The superconducting accelerator part of ADS Injector I mainly consists of 14 spoke-type superconducting cavities withβ0.12.At the same time,the research work of various cavities with differentβvalues and different frequencies is also carried out to lay the technical and technological foundation for ADS main accelerator.The only way to determine whether the superconducting cavity can reach the design target and whether it can be installed into the cryostat is the vertical test at cryogenic.As the only way to test the microwave performance of the superconducting cavity at low temperature,the vertical test can accurately test the acceleration gradient Eacc and the corresponding quality factor Q0 of the superconducting cavity.The design and construction of the superconducting cavity vertical test facility is based on the practical needs of the pilot project and the long-term development of the superconducting accelerator.Methods This paper mainly introduces the design and construction of the cryogenic vertical test system for the superconducting cavity of ADS Injector I,including the system scheme design,process design,heat load analysis,2 K superfluid helium obtaining method,system commissioning and operation,etc.Results and Conclusion The static heat leakage at 2 K of the 2 K superfluid helium vertical test system of ADS Injector I is 1.624W,which has reached the international advanced level.The 2 K superfluid helium vertical test system of ADS Injector I after constructed not only meets the test requirements of ADS pilot project,but also conducts 4 K and 2 K vertical tests for other different types of superconducting cavities and relevant cryogenic experiments.展开更多
The estimation of the external quality factor is important for designing coupling devices for the cavities.A new representation of the external quality factor calculations for single-cell cavity coupled to a coaxial t...The estimation of the external quality factor is important for designing coupling devices for the cavities.A new representation of the external quality factor calculations for single-cell cavity coupled to a coaxial transmission line is derived based on analytic analysis and numeric analysis with the help of 3D electromagnetic code,and verified with experimental measurements at room temperature.In logarithmic scale the results for the external quality factor were quasi-linear over the limited range,and the simulated and measured data could be used and extrapolated to the superconducting case.For the unpolished 1.5 GHz 3rd harmonic superconducting cavity,the discrepancy between the evaluation value and measurement result is less than 25% within an acceptable deviation.展开更多
To test superconducting cavities, a vertical test system has been designed and set up at the Institute of Modern Physics （IMP）. The system design is based on VCO-PLL hardware and the NI Labview software. The test of...To test superconducting cavities, a vertical test system has been designed and set up at the Institute of Modern Physics （IMP）. The system design is based on VCO-PLL hardware and the NI Labview software. The test of the HWR010#2 superconducting cavity shows that the function of this test system is satisfactory for testing the low frequency cavity.展开更多
A low loss- （LL） type 500 MHz 5-cell superconducting niobium prototype cavity with a large beam aperture has been developed successfully including the optimization, the deep drawing and electron beam welding, the su...A low loss- （LL） type 500 MHz 5-cell superconducting niobium prototype cavity with a large beam aperture has been developed successfully including the optimization, the deep drawing and electron beam welding, the surface treatment and the vertical testing. The performance of the fundamental mode was optimized and the higher order modes were damped by adopting an enlarged beam pipe for propagation. Surface preparation or treatment including mechanical polishing, buffered chemical polishing and high pressure rinsing with ultra-pure water and so on was carried out carefully to ensure a perfect inner surface condition. The vertical testing results show that the accelerating voltage higher than 7.5 MV was obtained while the quality factor was better than 1× 109 at 4.2 K. No obvious multipacting or field emission was found during the test. However, a quench happened while increasing the field a little higher than 7.5 MV that at present limited the cavity performance.展开更多
Superconducting cavities have been adopted in many kinds of accelerator facilities such as synchrotron radiation light source, hard X-ray free electron laser linac, colliders and energy recovery linacs (ERL). The 500 ...Superconducting cavities have been adopted in many kinds of accelerator facilities such as synchrotron radiation light source, hard X-ray free electron laser linac, colliders and energy recovery linacs (ERL). The 500 MHz superconducting cavities will be a candidate to be installed in the high current accelerators and high current ERLs for their large beam aperture, low higher order modes impedance and high current threshold value. This paper presents great progress in the whole sequence of developing 500 MHz superconducting cavity in China. It describes the first in-house successful development of 500 MHz single cell superconducting cavity including the deep-drawing of niobium half cells, electron beam wielding of cavity, surface preparations and vertical testing. The highest accelerating gradient of the fabricated cavity #SCD-02 higher than 10 MV/m was obtained while the quality factor was better than 4×108 at 4.2 K, which has reached the world level of the same kind of cavities.展开更多
文摘Purpose The accelerator-driven subcritical system(ADS)is the internationally recognized key technology of nuclear waste problem treatment,of which superconducting proton linac is an important part.With the support of the strategic science and technology pilot project of the Chinese Academy of Sciences,the Institute of High Energy Physics of the Chinese Academy of Sciences took the lead in the research of 325 MHz superconducting proton linac,which is called ADS Injector I.The superconducting accelerator part of ADS Injector I mainly consists of 14 spoke-type superconducting cavities withβ0.12.At the same time,the research work of various cavities with differentβvalues and different frequencies is also carried out to lay the technical and technological foundation for ADS main accelerator.The only way to determine whether the superconducting cavity can reach the design target and whether it can be installed into the cryostat is the vertical test at cryogenic.As the only way to test the microwave performance of the superconducting cavity at low temperature,the vertical test can accurately test the acceleration gradient Eacc and the corresponding quality factor Q0 of the superconducting cavity.The design and construction of the superconducting cavity vertical test facility is based on the practical needs of the pilot project and the long-term development of the superconducting accelerator.Methods This paper mainly introduces the design and construction of the cryogenic vertical test system for the superconducting cavity of ADS Injector I,including the system scheme design,process design,heat load analysis,2 K superfluid helium obtaining method,system commissioning and operation,etc.Results and Conclusion The static heat leakage at 2 K of the 2 K superfluid helium vertical test system of ADS Injector I is 1.624W,which has reached the international advanced level.The 2 K superfluid helium vertical test system of ADS Injector I after constructed not only meets the test requirements of ADS pilot project,but also conducts 4 K and 2 K vertical tests for other different types of superconducting cavities and relevant cryogenic experiments.
基金Supported by project Science and Technology Commission of Shanghai Municipality (026505027, 036505011)
文摘The estimation of the external quality factor is important for designing coupling devices for the cavities.A new representation of the external quality factor calculations for single-cell cavity coupled to a coaxial transmission line is derived based on analytic analysis and numeric analysis with the help of 3D electromagnetic code,and verified with experimental measurements at room temperature.In logarithmic scale the results for the external quality factor were quasi-linear over the limited range,and the simulated and measured data could be used and extrapolated to the superconducting case.For the unpolished 1.5 GHz 3rd harmonic superconducting cavity,the discrepancy between the evaluation value and measurement result is less than 25% within an acceptable deviation.
基金Supported by National Natural Science Foundation of China(91026001)
文摘To test superconducting cavities, a vertical test system has been designed and set up at the Institute of Modern Physics （IMP）. The system design is based on VCO-PLL hardware and the NI Labview software. The test of the HWR010#2 superconducting cavity shows that the function of this test system is satisfactory for testing the low frequency cavity.
基金Supported by National Natural Science Foundation of China(11175237)
文摘A low loss- （LL） type 500 MHz 5-cell superconducting niobium prototype cavity with a large beam aperture has been developed successfully including the optimization, the deep drawing and electron beam welding, the surface treatment and the vertical testing. The performance of the fundamental mode was optimized and the higher order modes were damped by adopting an enlarged beam pipe for propagation. Surface preparation or treatment including mechanical polishing, buffered chemical polishing and high pressure rinsing with ultra-pure water and so on was carried out carefully to ensure a perfect inner surface condition. The vertical testing results show that the accelerating voltage higher than 7.5 MV was obtained while the quality factor was better than 1× 109 at 4.2 K. No obvious multipacting or field emission was found during the test. However, a quench happened while increasing the field a little higher than 7.5 MV that at present limited the cavity performance.
文摘Superconducting cavities have been adopted in many kinds of accelerator facilities such as synchrotron radiation light source, hard X-ray free electron laser linac, colliders and energy recovery linacs (ERL). The 500 MHz superconducting cavities will be a candidate to be installed in the high current accelerators and high current ERLs for their large beam aperture, low higher order modes impedance and high current threshold value. This paper presents great progress in the whole sequence of developing 500 MHz superconducting cavity in China. It describes the first in-house successful development of 500 MHz single cell superconducting cavity including the deep-drawing of niobium half cells, electron beam wielding of cavity, surface preparations and vertical testing. The highest accelerating gradient of the fabricated cavity #SCD-02 higher than 10 MV/m was obtained while the quality factor was better than 4×108 at 4.2 K, which has reached the world level of the same kind of cavities.
