RuPAC2014 - Classification: 09 Superconducting accelerators and cryogenics

Paper

Title

Page

Comparision of Higher Order Modes Damping Techniques for Array of Single Cell Cavities

174

Ya.V. Shashkov, N.P. Sobenin
MEPhI, Moscow, Russia
M. Zobov
INFN/LNF, Frascati (Roma), Italy

Funding: Research supported by RFBR grant 13-02-00562/14 and EU FP7 HiLumi LHC - Grant Agreement 284404"
The LHC High Luminosity upgrade program considers an option of using additional cavities, operating at multiplies of the main RF system frequency of 400 MHz. Such harmonic cavities should provide a possibility to vary the length of colliding bunches. In order to supply the required harmonic voltage several single cell superconducting cavities are to be used. It is desirable to house more cavities in a single cryostat to reduce the number of transitions between "warm" and "cold" parts of the cryogenic system. In this paper we study electromagnetic characteristics of a chain of the single cell superconducting cavities coupled by drifts tubes. In order to reduce the influence of Higher order modes (HOM) excited in the structure on the beam stability and to minimize eventual power losses we analyze the HOM parameters and calculate the wake potential decay rates due to application of different HOM damping devices. In particular, the methods of HOM damping with rectangular waveguides connected to the drift tubes, the loads placed in the fluted and ridged drift tubes, as well as combinations of these methods are compared.
Higher order modes, superconductivity, harmonic cavities

THZ02

Facility for Assembling and Testing of SC Magnets for NICA and FAIR projects

S.A. Kostromin, H.G. Khodzhibagiyan
JINR, Dubna, Moscow Region, Russia

The NICA/MPD project has been started at the Joint Institute for Nuclear Research (JINR) in Dubna in 2007. The NICA accelerator complex will consist of two injector chains, the new 600 MeV/u superconducting (SC) booster synchrotron, the existing SC synchrotron Nuclotron, and the new SC collider having two rings each of 503 m in circumference. New test facility for simultaneous cryogenic testing of the SC magnets on 6 benches is under commisioning in the Laboratory of High Energy Physics (LHEP) JINR. Premises with an area of 2600 m2 were prepared to install the equipment. The 15 kA, 25 V pulse power supply, the helium satellite refrigerator with capacity of 100 W were commissioned first bench for magnets testing have being assembled and now is under commisioning. First magnets cryogenic tests are planned on October 2014. Start of the serial production of the SC magnets for the booster synchrotron is planned for the end of 2014.

Slides THZ02 [2.984 MB]

THZ03

Production of Superconducting Equipment at IHEP

301

L. Tkachenko, A.I. Ageev, I. Bogdanov, E. Kashtanov, S. Kozub, P.A. Shcherbakov, L.S. Shirshov, I. Slabodchikov, V. Sytnik, S. Zinchenko
IHEP, Moscow Region, Russia

The report overviews the recent SC-related R&D and production activity at IHEP. The scope of the paper extends over the items to follow. Two superconducting magnetic systems of Electron Lens for the Tevatron collider were developed, manufactured and successfully brought into operation. 42 cryogenic electrical feed boxes of various types for the Large Hadron Collider were developed, produced and commissioned. Results of development of fast-cycling SC magnets for the FAIR project are discussed. Operational experience acquired with the largest in Russia cryogenic system for cooling with a superfluid helium of SC RF separator for the beam transfer line #21from the U-70 machine is presented. Test-and-trial results with HTS current leads and dipole magnet employing Bi2223 as well as racetrack coils made of second-generation HTS are reviewed.

Slides THZ03 [0.823 MB]

THPSC15

Modernisation of the ILC Cryomodule Using High-tech Tchnology – Explosion Welding

B.M. Sabirov
JINR, Dubna, Moscow Region, Russia

The world first samples of Ti and Nb tubes joint with stainless steel ones by an explosion welding by the JINR-VNIIEF-FNAL-INFN cooperation were manufactured in the frame of ILC R&D program. An applying methods of relaxation of residual tensions (after explosion and electron beam welding), macro-and microanalyses of welding seam and cryogenic tests of the samples produced manifest the achievement of high mechanic strength (~250 MPa/share) of welding seam, solidity and leak absence on 10^-10 l*atm/sec level at 1.8 K. The explosion welding technology and methods introducing to industrial manufacturing of the 4-th generation of cryomodule of TESLA TYPE DESIGN can exclude the Ti – communications as cover of the vessel. The Agreement between JINR and E.Paton IEW (Kiev, Ukraine) was achieved for manufacturing Nb+SS transition samples using new technology and new design of Nb+Ti+SS junction. We suppose this samples should be more technological, simpler in manufacturing and cheaper.

THPSC16

Analysis of High Order Modes Damping Techniques for 800 MHz Single Cell Superconducting Cavities

353

Ya.V. Shashkov, N.P. Sobenin
MEPhI, Moscow, Russia
M. Zobov
INFN/LNF, Frascati (Roma), Italy

Funding: Research supported by RFBR grant 13-02-00562/14 and EU FP7 HiLumi LHC - Grant Agreement 284404
The High Luminosity LHC upgrade program foresees a possibility of using the second harmonic cavities working at 800 MHz for the collider bunch length variation. Such harmonic cavities should provide an opportunity to vary the length of colliding bunches. In order to supply the required harmonic voltage several single cell superconducting cavities are to be used. Different cavity designs and several higher order mode (HOM) damping techniques are being studied in order to reduce the cavity HOM impact on the beam stability and to minimize parasitic power losses. In this paper we analyze and compare the HOM electromagnetic characteristics and respective wake potential decay rates for cavities with grooves, fluted and ridged beam pipes. The problem of Lorentz force detuning is also addressed.

THPSC17

Higher Order Modes Damping for 9-cell Structure with Modified Drift Tubes

356

Ya.V. Shashkov, A.A. Mitrofanov, N.P. Sobenin
MEPhI, Moscow, Russia
V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

Funding: Research supported by RFBR grant 13-02-00562/14
This paper is focused on HOM damping in 9-cell superconducting cavities. We are considering HOM propagation outside from the cavity ridged and fluted drift tubes. The analysis of the influence of the parameters of the drift tube on the HOM damping was conducted. The considered methods were analysed and compared.

THPSC18

Suppression of Mechanical Oscillations in Quarterwave 10⁶ MHz Resonator

359

M. Gusarova, I.I. Petrushina, I.V. Rybakov, Ya.V. Shashkov, Ya.V. Shashkov, V. Zvyagintsev
MEPhI, Moscow, Russia
V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

Analytical calculations and numerical simulations have been done for mechanical eigenmodes of quarter wave superconducting resonators with operating frequency of 10⁶ MHz and 80 MHz. A possibility of frequency shift of mechanical modes in 106 MHz resonator has been estimated by application of the damper. We have optimized the damper's position for suppression efficiency. We have also compared the numerical and experimental results.

THPSC19

Influence of the Different Geometric Parameters of Superconducting Elliptical Cavities on the Multipactor

362

M. Gusarova, I.I. Petrushina
MEPhI, Moscow, Russia

The results of numerical simulations of multipacting in the different superconducting elliptical cavities are presented. Question of influence of the aperture radius, equator shape, iris shape and frequency and electron trajectories for different geometrical parameters of elliptic structures are considered.

THPSC20

Multipactor in Elliptical Cavities 800 MHz

365

M. Gusarova, I.I. Petrushina
MEPhI, Moscow, Russia

The studies of the multipacting discharge possibility in elliptic single-cell cavities at 800 MHz with three types of hifger order modes couplers were done. The ranges of the field gradients where the conditions for the occurrence of first order multipacting discharge in the equatorial region, as well as the HOM field levels were determined.

Paper	Title	Page
WEPSB09	Comparision of Higher Order Modes Damping Techniques for Array of Single Cell Cavities	174
	Ya.V. Shashkov, N.P. Sobenin MEPhI, Moscow, Russia M. Zobov INFN/LNF, Frascati (Roma), Italy
	Funding: Research supported by RFBR grant 13-02-00562/14 and EU FP7 HiLumi LHC - Grant Agreement 284404" The LHC High Luminosity upgrade program considers an option of using additional cavities, operating at multiplies of the main RF system frequency of 400 MHz. Such harmonic cavities should provide a possibility to vary the length of colliding bunches. In order to supply the required harmonic voltage several single cell superconducting cavities are to be used. It is desirable to house more cavities in a single cryostat to reduce the number of transitions between "warm" and "cold" parts of the cryogenic system. In this paper we study electromagnetic characteristics of a chain of the single cell superconducting cavities coupled by drifts tubes. In order to reduce the influence of Higher order modes (HOM) excited in the structure on the beam stability and to minimize eventual power losses we analyze the HOM parameters and calculate the wake potential decay rates due to application of different HOM damping devices. In particular, the methods of HOM damping with rectangular waveguides connected to the drift tubes, the loads placed in the fluted and ridged drift tubes, as well as combinations of these methods are compared. Higher order modes, superconductivity, harmonic cavities

THZ02	Facility for Assembling and Testing of SC Magnets for NICA and FAIR projects
	S.A. Kostromin, H.G. Khodzhibagiyan JINR, Dubna, Moscow Region, Russia
	The NICA/MPD project has been started at the Joint Institute for Nuclear Research (JINR) in Dubna in 2007. The NICA accelerator complex will consist of two injector chains, the new 600 MeV/u superconducting (SC) booster synchrotron, the existing SC synchrotron Nuclotron, and the new SC collider having two rings each of 503 m in circumference. New test facility for simultaneous cryogenic testing of the SC magnets on 6 benches is under commisioning in the Laboratory of High Energy Physics (LHEP) JINR. Premises with an area of 2600 m2 were prepared to install the equipment. The 15 kA, 25 V pulse power supply, the helium satellite refrigerator with capacity of 100 W were commissioned first bench for magnets testing have being assembled and now is under commisioning. First magnets cryogenic tests are planned on October 2014. Start of the serial production of the SC magnets for the booster synchrotron is planned for the end of 2014.
	Slides THZ02 [2.984 MB]

THZ03	Production of Superconducting Equipment at IHEP	301
	L. Tkachenko, A.I. Ageev, I. Bogdanov, E. Kashtanov, S. Kozub, P.A. Shcherbakov, L.S. Shirshov, I. Slabodchikov, V. Sytnik, S. Zinchenko IHEP, Moscow Region, Russia
	The report overviews the recent SC-related R&D and production activity at IHEP. The scope of the paper extends over the items to follow. Two superconducting magnetic systems of Electron Lens for the Tevatron collider were developed, manufactured and successfully brought into operation. 42 cryogenic electrical feed boxes of various types for the Large Hadron Collider were developed, produced and commissioned. Results of development of fast-cycling SC magnets for the FAIR project are discussed. Operational experience acquired with the largest in Russia cryogenic system for cooling with a superfluid helium of SC RF separator for the beam transfer line #21from the U-70 machine is presented. Test-and-trial results with HTS current leads and dipole magnet employing Bi2223 as well as racetrack coils made of second-generation HTS are reviewed.
	Slides THZ03 [0.823 MB]

THPSC15	Modernisation of the ILC Cryomodule Using High-tech Tchnology – Explosion Welding
	B.M. Sabirov JINR, Dubna, Moscow Region, Russia
	The world first samples of Ti and Nb tubes joint with stainless steel ones by an explosion welding by the JINR-VNIIEF-FNAL-INFN cooperation were manufactured in the frame of ILC R&D program. An applying methods of relaxation of residual tensions (after explosion and electron beam welding), macro-and microanalyses of welding seam and cryogenic tests of the samples produced manifest the achievement of high mechanic strength (~250 MPa/share) of welding seam, solidity and leak absence on 10^-10 l*atm/sec level at 1.8 K. The explosion welding technology and methods introducing to industrial manufacturing of the 4-th generation of cryomodule of TESLA TYPE DESIGN can exclude the Ti – communications as cover of the vessel. The Agreement between JINR and E.Paton IEW (Kiev, Ukraine) was achieved for manufacturing Nb+SS transition samples using new technology and new design of Nb+Ti+SS junction. We suppose this samples should be more technological, simpler in manufacturing and cheaper.

THPSC16	Analysis of High Order Modes Damping Techniques for 800 MHz Single Cell Superconducting Cavities	353
	Ya.V. Shashkov, N.P. Sobenin MEPhI, Moscow, Russia M. Zobov INFN/LNF, Frascati (Roma), Italy
	Funding: Research supported by RFBR grant 13-02-00562/14 and EU FP7 HiLumi LHC - Grant Agreement 284404 The High Luminosity LHC upgrade program foresees a possibility of using the second harmonic cavities working at 800 MHz for the collider bunch length variation. Such harmonic cavities should provide an opportunity to vary the length of colliding bunches. In order to supply the required harmonic voltage several single cell superconducting cavities are to be used. Different cavity designs and several higher order mode (HOM) damping techniques are being studied in order to reduce the cavity HOM impact on the beam stability and to minimize parasitic power losses. In this paper we analyze and compare the HOM electromagnetic characteristics and respective wake potential decay rates for cavities with grooves, fluted and ridged beam pipes. The problem of Lorentz force detuning is also addressed.

THPSC17	Higher Order Modes Damping for 9-cell Structure with Modified Drift Tubes	356
	Ya.V. Shashkov, A.A. Mitrofanov, N.P. Sobenin MEPhI, Moscow, Russia V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	Funding: Research supported by RFBR grant 13-02-00562/14 This paper is focused on HOM damping in 9-cell superconducting cavities. We are considering HOM propagation outside from the cavity ridged and fluted drift tubes. The analysis of the influence of the parameters of the drift tube on the HOM damping was conducted. The considered methods were analysed and compared.

THPSC18	Suppression of Mechanical Oscillations in Quarterwave 10⁶ MHz Resonator	359
	M. Gusarova, I.I. Petrushina, I.V. Rybakov, Ya.V. Shashkov, Ya.V. Shashkov, V. Zvyagintsev MEPhI, Moscow, Russia V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	Analytical calculations and numerical simulations have been done for mechanical eigenmodes of quarter wave superconducting resonators with operating frequency of 10⁶ MHz and 80 MHz. A possibility of frequency shift of mechanical modes in 106 MHz resonator has been estimated by application of the damper. We have optimized the damper's position for suppression efficiency. We have also compared the numerical and experimental results.

THPSC19	Influence of the Different Geometric Parameters of Superconducting Elliptical Cavities on the Multipactor	362
	M. Gusarova, I.I. Petrushina MEPhI, Moscow, Russia
	The results of numerical simulations of multipacting in the different superconducting elliptical cavities are presented. Question of influence of the aperture radius, equator shape, iris shape and frequency and electron trajectories for different geometrical parameters of elliptic structures are considered.

THPSC20	Multipactor in Elliptical Cavities 800 MHz	365
	M. Gusarova, I.I. Petrushina MEPhI, Moscow, Russia
	The studies of the multipacting discharge possibility in elliptic single-cell cavities at 800 MHz with three types of hifger order modes couplers were done. The ranges of the field gradients where the conditions for the occurrence of first order multipacting discharge in the equatorial region, as well as the HOM field levels were determined.