RuPAC2014 - List of Authors (Zobov, M.)

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

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.

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

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.