Paper | Title | Page |
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SUPCPA01 |
Measuring the Seebeck Coefficient at Cryogenic Temperatures for LCLS-II-HE Project | |
THPOGE15 | use link to access more material from this paper's primary paper code | |
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Funding: This work is supported by the DOE LCLS-II HE Project. The Seebeck effect plays a crucial role during the cooldown procedure in SRF based accelerators, like LCLS-II at SLAC. The temperature-dependent Seebeck coefficient quantitatively measures the strength of electric potential induced by thermal gradients in metals. This effect is present in cryomodules and drives thermoelectric currents generating magnetic fields. These fields can get trapped in cavities and cause additional dissipation in RF fields. We have therefore designed and commissioned an experimental setup that does continuous measurements of the Seebeck coefficient for cryogenic temperatures ranging from 200K down to below 10K. We present results of the measurements of this coefficient for materials commonly used in cryomodules, such as niobium, titanium, niobium-titanium, silicon bronze, and stainless steel. |
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Poster THPOGE15 [0.959 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE15 | |
About • | Received ※ 27 August 2022 — Revised ※ 04 September 2022 — Accepted ※ 26 September 2022 — Issue date ※ 29 September 2022 | |
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SUPCPA02 |
Investigation of HiPIMS-Coated S(I)S Structures for SRF Cavities | |
THPOGE02 | use link to access more material from this paper's primary paper code | |
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The sustainable next generation particle accelerators require innovative solutions to overcome the current technological challenges set by existing bulk niobium superconducting radio-frequency (SRF) cavities. Thin film-based multilayer structures in the form of superconductor-insulator-superconductor (SIS) may be the long-sought-after breakthrough for higher performance SRF cavities by enhancing both accelerating gradients and quality factors. In order to understand better the underlying mechanisms of SIS structures to be coated onto (S)RF cavities, we study various material properties with the resultant superconducting properties of high-power im-pulse magnetron sputtering (HiPIMS)-coated S(I)S structures of Nb-(AlN)-NbN with different thicknesses which are designed to be coated mainly on OFHC copper (Cu) samples for more efficient SRF cavities. This contribution presents materials properties of the aforementioned HiPIMS-coated S(I)S structures as well as the superconducting and RF behaviours of these multilayers which are assessed comparatively via DC and AC magnetization techniques. | ||
Poster THPOGE02 [0.747 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE02 | |
About • | Received ※ 25 August 2022 — Revised ※ 30 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 02 September 2022 | |
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SUPCPA03 |
Cavity R&D for HBS Accelerator | |
MOPOGE12 | use link to access more material from this paper's primary paper code | |
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The demand for neutrons of various types for research is growing day by day worldwide. To meet the growing demand the Jülich High Brilliance Neutron Source (HBS) is in development. It is based on a high power linear proton accelerator with an end energy of 70 MeV and a proton beam current of 100 mA. The main part of the accelerator consists of about 45 CH-type cavities. As the current beam dynamic layout is still work in progress the number of cavities can change for the final design. For this beam dynamic layout the design of the CH-type cavities was optimized to handle the high accelerating gradient. The results of the performance of the CH-type cavities will be presented in this paper. | ||
Poster MOPOGE12 [1.286 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOGE12 | |
About • | Received ※ 17 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 15 September 2022 | |
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SUPCPA04 |
RF Characterisation of Bulk Niobium and Thin Film Coated Planar Samples at 7.8 GHz | |
THPOGE10 | use link to access more material from this paper's primary paper code | |
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Research is ongoing into the use of superconducting thin films to replace bulk niobium for future radio frequency (RF) cavities. A key part of this research requires measuring the RF properties of candidate films. However, coating and testing thin films on full-sized cavities is both costly and time-consuming. Instead, films are typically deposited on small, flat samples and characterised using a test cavity. A cost-effective facility for testing such samples has recently been built and commissioned at Daresbury Laboratory. The facility allows for low power surface resistance measurements at a resonant frequency of 7.8 GHz, temperatures down to 4 K and sample surface magnetic fields up to 1 mT. A brief overview of this facility as well as recent results from measurements of both bulk Nb and thin film coated samples will be presented. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE10 | |
About • | Received ※ 24 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022 | |
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SUPCPA05 |
Operations of Copper Cavities at Cryogenic Temperatures | |
TUOPA06 | use link to access more material from this paper's primary paper code | |
TUPOGE18 | use link to access more material from this paper's primary paper code | |
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This work is focused on the anomalous skin effect in copper and how it affects the efficiency of copper-cavities in the temperature range 40-50 K. The quality factor Q of three coaxial cavities was measured over the temperature range from 10 K to room temperature in the experiment. The three coaxial cavities have the same structure, but different lengths, which correspond to resonant frequencies: around 100 MHz, 220 MHz and 340 MHz. Furthermore, the effects of copper-plating and additional baking in the vacuum oven on the quality factor Q are studied in the experiment. The motivation is to check the feasibility of an efficient, pulsed, ion linac, operated at cryogenic temperatures. | ||
Slides TUPOGE18 [1.115 MB] | ||
Poster TUPOGE18 [1.518 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOGE18 | |
About • | Received ※ 22 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 03 September 2022 | |
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SUPCPA06 |
Narrow Bandwidth Active Noise Control for Microphonics Rejection in Superconducting Cavities at LCLS-II | |
THPOPA21 | use link to access more material from this paper's primary paper code | |
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LCLS-II is an X-Ray Free Electron Laser (XFEL) under commissioning at SLAC, being the first Continuous Wave (CW) hard XFEL in the world to come into operation. To accelerate the electron beam to an energy of 4 GeV, 280 superconducting cavities of the TESLA types are used. A Loaded Q (QL) value of 4x107 is used to drive the cavities at a power level of a few kilowatts. For this QL value, the RF cavity bandwidth is equal to 32 Hz. Therefore, keeping the cavity resonance frequency within such bandwidth is imperative to avoid a significant increase in the required RF power. In superconducting accelerators, resonance frequency variations are produced by mechanical microphonic vibrations of the cavities. One source of microphonics noise is rotary machinery such as vacuum pumps or HVAC equipment. A possible method to reject these disturbances is to use Narrowband Active Noise Control (NANC) techniques. Such a technique was already tested at DESY/CMTB and Cornell/CBETA. This proceeding presents the implementation of a NANC controller in the LCLS-II Low Level RF (LLRF) control system. Tests on the rejection of LCLS-II microphonics disturbances are also presented. | ||
Poster THPOPA21 [1.843 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOPA21 | |
About • | Received ※ 24 August 2022 — Revised ※ 30 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 26 September 2022 | |
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SUPCPA08 |
Harmonic Bunch Formation and Optional RFQ Injection | |
TUPORI06 | use link to access more material from this paper's primary paper code | |
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With the aim of reduced beam emittances, a pre-bunching concept into an RFQ or a DTL has been developed. The structure has been designed by using a two harmonics double drift buncher which consists of two bunchers: the first one is driven by a fundamental frequency whereas the other is ex- cited with the second harmonic including a drift in between. This well-known "Harmonic Double-Drift-Buncher" is rein- vestigated under space charge conditions for RFQ, cyclotron, and for direct DTL-injection. There are significant benefits for this design such as to catch as many particles as possible from a dc beam into the longitudinal linac acceptance, or to reduce/optimize by up to an order of magnitude the lon- gitudinal emittance for low and medium beam currents. In accordance to these advantages, a new multi-particle track- ing beam dynamics code has been developed which is called "Bunch Creation from a DC beam - BCDC". In this paper we present this new code and some stimulating examples. | ||
Poster TUPORI06 [28.234 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPORI06 | |
About • | Received ※ 24 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 05 September 2022 | |
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SUPCPA09 |
Emittance Measurement from the Proton Testbeam at KAHVELab | |
TUPORI17 | use link to access more material from this paper's primary paper code | |
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Funding: This study is supported by Istanbul University Scientific Research Commission Project ID 33250 and TUBITAK Project no : 119M774. A testbeam using a Radio Frequency Quadrupole (RFQ) operating at 800 MHz, to accelerate a 1.5mA proton beam to 2MeV energy has been designed, manufactured and is currently being commissioned at KAHVELab, Istanbul. The beam from the microwave discharge ion source (IS) must be matched to the RFQ via an optimized Low Energy Beam Transport (LEBT) line. The LEBT line consists of two solenoid magnets, two stereer magnets and a beam diagnostics station named MBOX. All the beamline components are locally designed, simulated, manufactured and tested with local resources. The MBOX should be able to measure the beam current and profile, as well as the beam emittance, to ensure an accurate match between IS and RFQ. It includes a number of diagnostic tools: a Faraday Cup, a scintillator screen, and a pepper pot plate (PP). An analysis software is developed and tested for the PP photo analysis. This contribution will present the proton beamline components and will focus on the MBOX measurements, especially on the PP emittance analysis. |
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Poster TUPORI17 [5.641 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPORI17 | |
About • | Received ※ 23 August 2022 — Revised ※ 09 September 2022 — Accepted ※ 26 September 2022 — Issue date ※ 29 September 2022 | |
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