RF Surface Technology Research Group was founded in August 2019.It was evolved from the former Supercon-ducting Radio Frequency(SRF)research group of Linac center.The primary research topics will be presented in this ...RF Surface Technology Research Group was founded in August 2019.It was evolved from the former Supercon-ducting Radio Frequency(SRF)research group of Linac center.The primary research topics will be presented in this report.展开更多
After many years of worldwide exploration and improvement of the post treatment process,niobium(Nb)cavities are now approaching their fundamental limits both in terms of maximum acceleration field and in terms of surf...After many years of worldwide exploration and improvement of the post treatment process,niobium(Nb)cavities are now approaching their fundamental limits both in terms of maximum acceleration field and in terms of surface resistance at typical operating temperatures.展开更多
Field emission occurred in superconducting radio-frequency(SRF)cavities is the major obstacle of the accelerators operating at high gradient,which partly caused by the inner surface contamination,such as the hydrocarb...Field emission occurred in superconducting radio-frequency(SRF)cavities is the major obstacle of the accelerators operating at high gradient,which partly caused by the inner surface contamination,such as the hydrocarbons and the absorbed residual gas.The plasma processing can be an effective method to solve the field emission issues.The properties of low temperature glow discharge,which was argon plasma with the chemically reactive oxygen,were investigated for the SRF cavities used for CADS project.展开更多
SRF cavities are operated at Meissner state,which al-lows the electro-magnetic wave only interacts with the very surface of the cavity.The penetration depth of Nb at 4.2 is^100 nm,which means more than 99%of the expen...SRF cavities are operated at Meissner state,which al-lows the electro-magnetic wave only interacts with the very surface of the cavity.The penetration depth of Nb at 4.2 is^100 nm,which means more than 99%of the expensive SRF grade Nb used on the SRF cavity is not involved in the interaction with the E-M wave.Fig.1 shows the schematics diagram of the interac-tion between magnetic field and a Nb coated Cu cavity.With a Nb film thicker than 3λ,the copper hide behind wouldn't be able to see the E-M wave nor generate RF dissipation.展开更多
The BCP solutions use mixed acids based on HF acid,which carry significant potential safety hazard during operation.Developing a safe and green polishing solution without HF is an important research subject for cavity...The BCP solutions use mixed acids based on HF acid,which carry significant potential safety hazard during operation.Developing a safe and green polishing solution without HF is an important research subject for cavity’s surface treatment[1].We adopt green ionic liquids for polishing solution of electropolish niobium samples.In the experiment,niobium samples were electropolished from a 1:2:1 Choline chloride–urea-ammonium fluoride ionic liquid under different conditions(Fig.1).The surface of Nb sample without any treatment is dark and uneven(1#of Fig.1).After electropolished at 50℃,the surface of Nb sample become smooth,but the glossiness is not good(2#of Fig.1).Improving the electropolishing temperature to 80℃,the glossiness of Nb becomes good and the surface becomes even(3#of Fig.1).In order to compare the electropolishing effect intuitively,put a ruler before the treated samples.展开更多
文摘RF Surface Technology Research Group was founded in August 2019.It was evolved from the former Supercon-ducting Radio Frequency(SRF)research group of Linac center.The primary research topics will be presented in this report.
文摘After many years of worldwide exploration and improvement of the post treatment process,niobium(Nb)cavities are now approaching their fundamental limits both in terms of maximum acceleration field and in terms of surface resistance at typical operating temperatures.
文摘Field emission occurred in superconducting radio-frequency(SRF)cavities is the major obstacle of the accelerators operating at high gradient,which partly caused by the inner surface contamination,such as the hydrocarbons and the absorbed residual gas.The plasma processing can be an effective method to solve the field emission issues.The properties of low temperature glow discharge,which was argon plasma with the chemically reactive oxygen,were investigated for the SRF cavities used for CADS project.
文摘SRF cavities are operated at Meissner state,which al-lows the electro-magnetic wave only interacts with the very surface of the cavity.The penetration depth of Nb at 4.2 is^100 nm,which means more than 99%of the expensive SRF grade Nb used on the SRF cavity is not involved in the interaction with the E-M wave.Fig.1 shows the schematics diagram of the interac-tion between magnetic field and a Nb coated Cu cavity.With a Nb film thicker than 3λ,the copper hide behind wouldn't be able to see the E-M wave nor generate RF dissipation.
文摘The BCP solutions use mixed acids based on HF acid,which carry significant potential safety hazard during operation.Developing a safe and green polishing solution without HF is an important research subject for cavity’s surface treatment[1].We adopt green ionic liquids for polishing solution of electropolish niobium samples.In the experiment,niobium samples were electropolished from a 1:2:1 Choline chloride–urea-ammonium fluoride ionic liquid under different conditions(Fig.1).The surface of Nb sample without any treatment is dark and uneven(1#of Fig.1).After electropolished at 50℃,the surface of Nb sample become smooth,but the glossiness is not good(2#of Fig.1).Improving the electropolishing temperature to 80℃,the glossiness of Nb becomes good and the surface becomes even(3#of Fig.1).In order to compare the electropolishing effect intuitively,put a ruler before the treated samples.
