<p>The China Spallation Neutron Source (CSNS) is the fourth pulsed accelerator-driven neutron source in the world, and it achieved its design target of 100 kW in 2020. The planned China Spallation Neutron Source Phase II (CSNS-II) commenced in 2024. The CSNS-II linac design primarily involves the addition of a radio-frequency ion source and a section of a superconducting linear accelerator composed of two types of superconducting cavities, namely double-spoke and six-cell elliptical cavities, after the drift tube linac (DTL). The development of the double-spoke superconducting cavity began in early 2021, and by January 2023, the welding, post-processing, and vertical tests of two 324 MHz double-spoke cavity prototypes were completed, with vertical test gradients of 11.6 and 15 MV/m, and <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1716_Article_IEq1.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="22" /> </InlineMediaObject> <EquationSource Format="TEX">$Q_{0}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>Q</mi> <mn>0</mn> </msub> </math></EquationSource> </InlineEquation> <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1716_Article_IEq2.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">$\ge$</EquationSource> <EquationSource Format="MATHML"><math> <mo>≥</mo> </math></EquationSource> </InlineEquation> <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1716_Article_IEq3.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="58" /> </InlineMediaObject> <EquationSource Format="TEX">$3\times 10^{10}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>3</mn> <mo>×</mo> <msup> <mn>10</mn> <mn>10</mn> </msup> </mrow> </math></EquationSource> </InlineEquation> @ <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1716_Article_IEq4.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="121" /> </InlineMediaObject> <EquationSource Format="TEX">$E_\text {acc}\le {10}\,\text{MV/m}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>E</mi> <mtext>acc</mtext> </msub> <mo>≤</mo> <mn>10</mn> <mspace width="0.166667em" /> <mtext>MV/m</mtext> </mrow> </math></EquationSource> </InlineEquation>. The R&D of the cryomodule began in January 2022. In October 2023, the clean assembly of the double-spoke cavity string and cold mass installation of the cryomodule commenced, with the installation of the cryomodule and valve box completing in two months. In January 2024, a horizontal test of the cryomodule was completed, making it the first double-spoke cavity cryomodule in China. The test results showed that the maximum gradients of the two superconducting cavities at a pulse width of 4 ms and repetition frequency of 25 Hz were 12.8 and 15.2 MV/m, respectively. This article provides a detailed introduction to the double-spoke superconducting cavity, tuner, coupler, and cryomodule, elaborates on the clean assembly of the cavity string and cold mass installation of the cryomodule, and provides a detailed analysis of the horizontal test results.</p>

Integration and horizontal testing of the CSNS-II double-spoke cavity cryomodule

期刊论文
发表日期：

2025年6月4日

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Wei-Min Pan,
Wen-Zhong Zhou,
Fei-Si He,
Rui Ge,
Miao-Fu Xu,
Zheng-Hui Mi,
Jin Dai,
Ye Han,
Mei Li,
Zhe-Xin Xie,
Ming Liu,
Qun-Yao Wang,
Hai-Ying Lin,
Bai-Qi Liu,
Xiao-Long Wang,
Zhen-Qiang He,
Tong-Ming Huang,
Qiang Ma,
Xu Chen,
Min-Jing Sang,
Ke-Yu Zhu,
Tong-Xian Zhao,
Chang-Cheng Ma,
Rui Ye,
Zheng-Ze Chang,
Liang-Rui Sun,
Meng-Xu Fan,
Cong Zhang,
Hua-Chang Liu,
Zhen-Cheng Mu,
Tong Wang,
Bin Ye,
Yang Meng,
Lin-Yang Rong,
Hui Zhang,
Bo Wang,
Ma-Liang Wan,
Yun Wang,
Sheng Wang

摘要

The China Spallation Neutron Source (CSNS) is the fourth pulsed accelerator-driven neutron source in the world, and it achieved its design target of 100 kW in 2020. The planned China Spallation Neutron Source Phase II (CSNS-II) commenced in 2024. The CSNS-II linac design primarily involves the addition of a radio-frequency ion source and a section of a superconducting linear accelerator composed of two types of superconducting cavities, namely double-spoke and six-cell elliptical cavities, after the drift tube linac (DTL). The development of the double-spoke superconducting cavity began in early 2021, and by January 2023, the welding, post-processing, and vertical tests of two 324 MHz double-spoke cavity prototypes were completed, with vertical test gradients of 11.6 and 15 MV/m, and $Q_{0}$ $Q_{0}$ $\ge$ $\geq$ $3\times 10^{10}$ $3 \times 10^{10}$ @ $E_\text {acc}\le {10}\,\text{MV/m}$ $E_{acc} \leq 10 MV/m$ . The R&D of the cryomodule began in January 2022. In October 2023, the clean assembly of the double-spoke cavity string and cold mass installation of the cryomodule commenced, with the installation of the cryomodule and valve box completing in two months. In January 2024, a horizontal test of the cryomodule was completed, making it the first double-spoke cavity cryomodule in China. The test results showed that the maximum gradients of the two superconducting cavities at a pulse width of 4 ms and repetition frequency of 25 Hz were 12.8 and 15.2 MV/m, respectively. This article provides a detailed introduction to the double-spoke superconducting cavity, tuner, coupler, and cryomodule, elaborates on the clean assembly of the cavity string and cold mass installation of the cryomodule, and provides a detailed analysis of the horizontal test results.