PAC2013 - List of Authors (Khabiboulline, T.N.)

Paper	Title	Page
WEPAC21	Tuning Process of SSR1 Cavity for Project X at FNAL	832
	P. Berrutti, M.H. Awida, T.N. Khabiboulline, D. Passarelli, L. Ristori, V.P. Yakovlev Fermilab, Batavia, USA
	SSR1 is a family of single spoke resonators to be used in Project X at Fermi National Laboratory. These cavities operate in CW regime having nominal frequency of 325 MHz and optimal beta of 0.22. SSR1 cavities will accelerate H⁻ ions after the Half Wave Resonator (HWR) section from 9 MeV to 32 MeV. In the near future this cavity will be used in Project X Injector Experiment (PXIE), which contains the ion source, the LEBT, the MEBT, the RFQ of Project X, and a cryogenic temperature section, having one HWR and one SSR1 cryomodule. SSR1 cavities have been built and tested at FNAL, the preparation of these resonators includes RF tuning which is the main focus of this paper. The frequency of the cavity is carefully chosen prior to the vertical test, and it is adjusted before welding the helium vessel to obtain 325 MHz nominal frequency for the dressed cavity in operating conditions. Several SSR1 cavities have been tuned at FNAL, the procedure, the hardware and the data are presented.

WEPAC22	Single Spoke Resonator Inner Electrode Optimization Driven by Reduction of Multipoles	835
	P. Berrutti, T.N. Khabiboulline, L. Ristori, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	Accelerating cavities based on coaxial resonators, half wave and spoke resonators for example, do not have azimuthal symmetry. This lack of symmetry introduces a transverse field perturbation which affects the beam dynamic, since the particles traveling through the structure are crossing two accelerating gaps separated by the inner electrode. The field asymmetry induces an asymmetric transverse momentum gain which, once expanded in multipoles, appears to be due to a quadrupole perturbation. Depending on the cavity geometry and particle velocity, the influence of electric and magnetic fields may vary quite significantly. A way of having symmetric transverse fields in spoke resonators consists in modifying the inner electrode from a pole to an X or Y shape. The application of these changes symmetrizes both electric and magnetic fields and reduces the multipoles amplitudes to negligible values. This paper presents the study aimed to reduce the multi-poles amplitudes of SSR2 cavity for Project X; the presented procedure, in general, is valid for any spoke cavity.

WEPAC23	Multipacting Simulations of SSR2 Cavity at FNAL	838
	P. Berrutti, T.N. Khabiboulline, L. Ristori, G.V. Romanov, A.I. Sukhanov, V.P. Yakovlev Fermilab, Batavia, USA
	SSR2 is the second family of single spoke resonator under development at Fermi National Accelerator Laboratory (FNAL). These cavities will be placed in Project X front-end after SSR1 spoke resonators, which have already been built and tested and FNAL. Spoke cavities are affected by multipacting and the nature of their 3D geometry does not allow simulating the multipactor process using 2D tools. 3D tracking simulations, of electrons inside the cavity volume, have been carried out using CST Particle Studio. Different Secondary Emission Coefficients have been applied to the cavity walls in order to understand how strongly the multipacting depends on material properties. The power levels used in simulations cover the whole operating gradient range of SSR2 cavity. Results of these simulations are compared to the one given by SSR1 model, which demonstrated good agreement with experimental data. The purposes of this paper are to present the results gotten from the tracking solver, to give a prediction of what will be the multipacting scenario for SSR2 cavity and if there will be any dangerous zone for operation.

WEPAC25	New Helium Vessel and Lever Tuner Designs for the 650 MHz Cavities for Project X	841
	I.V. Gonin, M.H. Awida, E. Borissov, M.H. Foley, C.J. Grimm, T.N. Khabiboulline, M. Merio, Y.M. Pischalnikov, L. Ristori, V.P. Yakovlev Fermilab, Batavia, USA
	The design of 5-cell elliptical 650 MHz β=0.9 cavities to accelerate H⁻ beam of 1 mA average current in the range 467-3000 MeV for the Project X Linac is currently under development at Fermilab. A new design of the Helium Vessel (HV) was developed for these cavities with the main goal of optimizing the frequency sensitivity df/dP by keeping the cavity stiffness reasonably small. We also present a design of the new lever tuner system. The HV in the new design is equipped with the tuner located at the end of the cavity instead of the initially proposed blade tuner located in the middle. We will present mechanical design results and ANSYS analyses for both the slow and fast tuners.

WEPAC29	CM2, Second 1.3GHz Cryomodule Fabrication at Fermilab	844
	T.T. Arkan, M.H. Awida, P. Berrutti, E. Borissov, C.M. Ginsburg, C.J. Grimm, E.R. Harms, A. Hocker, T.N. Khabiboulline, Y.O. Orlov, T.J. Peterson, R.V. Pilipenko, Y.M. Pischalnikov, K.S. Premo, L. Ristori, W. Schappert, V.P. Yakovlev Fermilab, Batavia, USA
	Funding: US Department of Energy CM2 is the second 1.3GHz Cryomodule assembled at the Cryomodule Assembly Facility (CAF) in Fermi National Accelerator Laboratory. The string has a doublet magnet, beam position monitor and eight cavities. All the cavities are qualified at 35 MV / m gradient at the Horizontal Test Facility before assembly. The dressed cavities were outfitted with magnetic shielding, blade tuner, and the cold mass was assembled based on the Tesla TTF Type III+ cryomodule design. CM2 is currently being installed into the test stand in NML where it will be cooled down and high power tested. CM2 will also be the first cryomodule that an electron beam will be put through at the NML facility. This will be a proof of principle for the planned Advanced Superconducting Test Accelerator (ASTA) facility at NML. This paper describes the assembly steps, the quality assurance methods and the challenges that we experienced during assembly and qualification steps at CAF. De

WEPAC32	Wakefield Loss Analysis of the Elliptical 3.9 GHz Third Harmonic Cavity	847
	M.H. Awida, P. Berrutti, T.N. Khabiboulline, A. Saini, V.P. Yakovlev Fermilab, Batavia, USA
	Third harmonic 3.9 GHz elliptical cavities are planned to be used in many particle accelerator projects such as XFEL, NGLS, and ASTA. In this paper, the wakefield losses due to single bunch passage are analysed considering bunches of RMS length 8 mm down to ultra short ones of 10 μm length. Both the loss and kick factors are numerically calculated for bunches of relatively long length (>1 mm) using CST wakefield solver. The data is then used to extrapolate asymptotically the values for ultra-short bunches by finding the wake functions. These calculations are essential to estimate the cryogenic losses in cryomodules and for beam dynamic analysis.

Paper

Title

Page

Tuning Process of SSR1 Cavity for Project X at FNAL

832

P. Berrutti, M.H. Awida, T.N. Khabiboulline, D. Passarelli, L. Ristori, V.P. Yakovlev
Fermilab, Batavia, USA

SSR1 is a family of single spoke resonators to be used in Project X at Fermi National Laboratory. These cavities operate in CW regime having nominal frequency of 325 MHz and optimal beta of 0.22. SSR1 cavities will accelerate H⁻ ions after the Half Wave Resonator (HWR) section from 9 MeV to 32 MeV. In the near future this cavity will be used in Project X Injector Experiment (PXIE), which contains the ion source, the LEBT, the MEBT, the RFQ of Project X, and a cryogenic temperature section, having one HWR and one SSR1 cryomodule. SSR1 cavities have been built and tested at FNAL, the preparation of these resonators includes RF tuning which is the main focus of this paper. The frequency of the cavity is carefully chosen prior to the vertical test, and it is adjusted before welding the helium vessel to obtain 325 MHz nominal frequency for the dressed cavity in operating conditions. Several SSR1 cavities have been tuned at FNAL, the procedure, the hardware and the data are presented.

WEPAC22

Single Spoke Resonator Inner Electrode Optimization Driven by Reduction of Multipoles

835

P. Berrutti, T.N. Khabiboulline, L. Ristori, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

Accelerating cavities based on coaxial resonators, half wave and spoke resonators for example, do not have azimuthal symmetry. This lack of symmetry introduces a transverse field perturbation which affects the beam dynamic, since the particles traveling through the structure are crossing two accelerating gaps separated by the inner electrode. The field asymmetry induces an asymmetric transverse momentum gain which, once expanded in multipoles, appears to be due to a quadrupole perturbation. Depending on the cavity geometry and particle velocity, the influence of electric and magnetic fields may vary quite significantly. A way of having symmetric transverse fields in spoke resonators consists in modifying the inner electrode from a pole to an X or Y shape. The application of these changes symmetrizes both electric and magnetic fields and reduces the multipoles amplitudes to negligible values. This paper presents the study aimed to reduce the multi-poles amplitudes of SSR2 cavity for Project X; the presented procedure, in general, is valid for any spoke cavity.

WEPAC23

Multipacting Simulations of SSR2 Cavity at FNAL

838

P. Berrutti, T.N. Khabiboulline, L. Ristori, G.V. Romanov, A.I. Sukhanov, V.P. Yakovlev
Fermilab, Batavia, USA

SSR2 is the second family of single spoke resonator under development at Fermi National Accelerator Laboratory (FNAL). These cavities will be placed in Project X front-end after SSR1 spoke resonators, which have already been built and tested and FNAL. Spoke cavities are affected by multipacting and the nature of their 3D geometry does not allow simulating the multipactor process using 2D tools. 3D tracking simulations, of electrons inside the cavity volume, have been carried out using CST Particle Studio. Different Secondary Emission Coefficients have been applied to the cavity walls in order to understand how strongly the multipacting depends on material properties. The power levels used in simulations cover the whole operating gradient range of SSR2 cavity. Results of these simulations are compared to the one given by SSR1 model, which demonstrated good agreement with experimental data. The purposes of this paper are to present the results gotten from the tracking solver, to give a prediction of what will be the multipacting scenario for SSR2 cavity and if there will be any dangerous zone for operation.

WEPAC25

New Helium Vessel and Lever Tuner Designs for the 650 MHz Cavities for Project X

841

I.V. Gonin, M.H. Awida, E. Borissov, M.H. Foley, C.J. Grimm, T.N. Khabiboulline, M. Merio, Y.M. Pischalnikov, L. Ristori, V.P. Yakovlev
Fermilab, Batavia, USA

The design of 5-cell elliptical 650 MHz β=0.9 cavities to accelerate H⁻ beam of 1 mA average current in the range 467-3000 MeV for the Project X Linac is currently under development at Fermilab. A new design of the Helium Vessel (HV) was developed for these cavities with the main goal of optimizing the frequency sensitivity df/dP by keeping the cavity stiffness reasonably small. We also present a design of the new lever tuner system. The HV in the new design is equipped with the tuner located at the end of the cavity instead of the initially proposed blade tuner located in the middle. We will present mechanical design results and ANSYS analyses for both the slow and fast tuners.

WEPAC29

CM2, Second 1.3GHz Cryomodule Fabrication at Fermilab

844

T.T. Arkan, M.H. Awida, P. Berrutti, E. Borissov, C.M. Ginsburg, C.J. Grimm, E.R. Harms, A. Hocker, T.N. Khabiboulline, Y.O. Orlov, T.J. Peterson, R.V. Pilipenko, Y.M. Pischalnikov, K.S. Premo, L. Ristori, W. Schappert, V.P. Yakovlev
Fermilab, Batavia, USA

Funding: US Department of Energy
CM2 is the second 1.3GHz Cryomodule assembled at the Cryomodule Assembly Facility (CAF) in Fermi National Accelerator Laboratory. The string has a doublet magnet, beam position monitor and eight cavities. All the cavities are qualified at 35 MV / m gradient at the Horizontal Test Facility before assembly. The dressed cavities were outfitted with magnetic shielding, blade tuner, and the cold mass was assembled based on the Tesla TTF Type III+ cryomodule design. CM2 is currently being installed into the test stand in NML where it will be cooled down and high power tested. CM2 will also be the first cryomodule that an electron beam will be put through at the NML facility. This will be a proof of principle for the planned Advanced Superconducting Test Accelerator (ASTA) facility at NML. This paper describes the assembly steps, the quality assurance methods and the challenges that we experienced during assembly and qualification steps at CAF. De

WEPAC32

Wakefield Loss Analysis of the Elliptical 3.9 GHz Third Harmonic Cavity

847

M.H. Awida, P. Berrutti, T.N. Khabiboulline, A. Saini, V.P. Yakovlev
Fermilab, Batavia, USA

Third harmonic 3.9 GHz elliptical cavities are planned to be used in many particle accelerator projects such as XFEL, NGLS, and ASTA. In this paper, the wakefield losses due to single bunch passage are analysed considering bunches of RMS length 8 mm down to ultra short ones of 10 μm length. Both the loss and kick factors are numerically calculated for bunches of relatively long length (>1 mm) using CST wakefield solver. The data is then used to extrapolate asymptotically the values for ultra-short bunches by finding the wake functions. These calculations are essential to estimate the cryogenic losses in cryomodules and for beam dynamic analysis.