| Paper | Title | Page |
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| MOPEC081 | The Concept Design of the CW Linac of the Project X | 654 |
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The concept design of the 2.5 GeV superconducting CW linac of the Project X is discussed. The linac structure and break points for different cavity families are described. The results of the RF system optimization are presented as well as the lattice design and beam dynamics analysis. |
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| MOPEC082 | Lattice Design for Project -X CW Superconducting Linac | 657 |
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In this paper, we discuss beam dynamics optimization for a proposed continuous wave (CW) Project-X superconducting (SC) linac. This 2.6 GeV linac has an average current (over few microseconds) of 1 mA, with a pulsed current of up to 5-10 mA. The beam power is 2.6 MW. The CW linac consists of a low-energy 325 MHz section (2.5 MeV - 470 MeV) containing three families of SC single-spoke resonators and one family of triple-spoke resonators followed by a high-energy 1.3 GHz SC section (470 MeV - 2.6 GeV) containing squeezed elliptical (β=0.81) and ILC-type (β=1) cavities. Transverse and longitudinal dynamics in the CW linac are modeled assuming a peak current 10 mA. Different options for focusing structures are considered: solenoidal, doublet, and triplet focusing in the low-energy section; FODO and doublet focusing in the high energy section. |
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| MOPD061 | 650 MHz Option for High-energy Part of the Project X linac | 825 |
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650 MHz option for the high energy part of the 2.6 GeV, CW Project X linac is discussed. It may give significant benefits compared to current 1.3 GHz option based on the utilization of ILC-type beta=1 cavities. Results of the break point optimization for linac stages, cavity optimization and beam dynamics optimization are presented. Possible reduction in the number of cryomodules and linac length compared to the current linac project version is discussed. Cryogenic losses are analyzed also. |
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| MOPE087 | Submicron Multi-bunch BPM for CLIC | 1185 |
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A common-mode free cavity BPM is currently under development at Fermilab within the ILC-CLIC collaboration. This monitor will be operated in a CLIC Main Linac multi-bunch regime, and needs to provide both, high spatial and time resolution. We present the design concept, numerical analysis, investigation on tolerances and error effects, as well as simulations on the signal response applying a multi-bunch stimulus. |
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| TUPEA020 | Longitudinal and Transverse Effects of HOMs in the Project X Linac | 1369 |
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Results of analysis are presented for the longitudinal and transverse effects of High-Order Mode (HOM) excitation in the acceleration RF system of the CW proton linac of the Project X facility. Necessity of HOM dampers in the SC cavities of the linac is discussed. |
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| WEPEC009 | Designing of 9 Cell Reduced Beta Elliptical Cavity for High Intensity Proton Linac | 2908 |
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A superconducting rf cavity is designed for acceleration of particles travelling at 81% the speed of light. The cavity will operate at 1.3 GHz & is to be used in SILC section of the proposed high intensity proton linac at Fermilab. At present cavity will serve to accelerate the particles for energy range 466 MeV to 1.2 GeV. The cavity will be shorter than 9 cell beta =1 cavity but nearly same ratio of surface magnetic field to surface electric field. Cell to cell coupling coefficient is also optimized to get the good field flatness. The cavity is studied for monopole modes and higher order modes. The shapes of end cells are optimized to avoid dangerous modes with keeping same field flatness & same operating frequency. |
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| WEPEC010 | Optimization of End Cells of Low Beta Cavity of Higher Energy Part of Project X | 2911 |
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Eleven cell elliptical cavity is designed for acceleration of particles traveling at 81 % of the speed of light. It will operate at 1.3 GHz and will be used to accelerate the particles from 0.4 GeV to 1.2 GeV. The cavity is studied for higher order mode (HOM) and trapped modes. The shapes of end cells of cavity is optimized to increase the field amplitude in end cells so that coupling of trapped modes may increase with HOM coupler and they can be extracted easily but keeping the field flatness & operating frequency undisturbed. |
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| WEPEC057 | Single Spoke Cavities for Low-energy Part of CW Linac of Project X. | 3022 |
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In the low-energy part of the Project X H-linac there families of 325 MHz SC single spoke cavities will be used, having beta = 0.11, 0.22 and 0.4. Two versions of the beta = 0.11 cavity were considered: low-beta single-spoke cavity and half-wave cavity. Results of detailed optimization of both versions are presented. Single spoke cavity was selected for the linac because of higher r/Q. Results of the beam dynamics optimization for initial stage of the linac with beta=0.11 single spoke cavity are presented as well. |
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| WEPEC059 | The Beam Splitter for the Project X | 3025 |
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In the Project X facility a 2.6 GeV, H- CW beam is delivered to three users simultaneously by way of selectively filling appropriate RF buckets at the front end of the linac and then RF splitting them to three different target halls. With the desire to split the H- beam three ways, an RF separator directs two quarters of the beam to one user (Mu2e), one quarter to another user (Kaon), and one quarter to the third (unidentified) user. The natural way is to use a SC structure with the deflecting TM110 mode. Basic requirements to the deflecting RF structure are formulated and design of the deflecting SC cavities is presented. |
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| WEPE034 | Final Results on RF and Wake Kicks Caused by the Couplers for the ILC Cavity | 3431 |
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In the paper the results are presented for calculation of the transverse wake and RF kick from the power and HOM couplers of the ILC acceleration structure. The RF kick was calculated stand-alone by HFSS, CST MWS and COMSOL codes while the wake kick was calculated by GdfidL. The calculation precision and convergence for both cases are discussed and compared to the results obtained independently by other group. |
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| THPEB051 | Observation of an Anomalous Tuning Range of a Doped BST Ferroelectric Material Developed for Accelerator Applications | 3987 |
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The BST based ferroelectric-oxide compounds have been found as suitable materials for a fast electrically-controlled RF switches and phase shifters that are under development for accelerator applications in X, Ka and L - frequency bands. The BST(M) material (BST ferroelectric with Mg-based additives) allows fast switching and tuning in vacuum and in air both; switching time of material samples < 10 ns has been demonstrated*. One of the problems related to accelerator application of BST ferroelectric is its high dielectric constant. Decreasing the permittivity however is usually strongly correlated with a decrease in the tunability (k(E)=ε(0)/ε(E)) of ferroelectrics. The use of linear dielectric inclusions in BST ceramics could result in significant suppression of the mentioned k(E) dependence, with the best case being that the tunability vs. ε decrease could be unchanged. On the basis of our measurements we report here two unusual phenomena observed**: (i) the increase both the dc and the dynamic tunability with a decrease of the dielectric constant; (ii) the dynamic tunability was observed to exceed the static tunability at specific magnitudes of the applied field. * A.Kanareykin et al, Proceedings PAC'09. |
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| THPD069 | Studies of Nonlinear Media with Accelerator Applications | 4440 |
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Materials possessing variations in the permittivity as a function of the electric field exhibit a variety of phenomena for electromagnetic wave propagation such as frequency multiplication, wave steepening and shock formation, solitary waves, and mode mixing. New low loss nonlinear microwave ferroelectric materials present interesting and potentially useful applications for both advanced and conventional particle accelerators. Accelerating structures (either wakefield-based or driven by an external rf source) loaded with a nonlinear dielectric may exhibit significant field enhancements. In this paper we will explore the large signal permittivity of these new materials and applications of nonlinear dielectric devices to high gradient acceleration, rf sources, and beam manipulation. We describe planned measurements using a planar nonlinear transmission line to characterize in detail the electric field dependence of the permittivity of these materials. We will present a concept for a nonlinear transmission line that can be used to generate short, high intensity rf pulses to drive fast rf kickers. |
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| THPD088 | Study of Coupler's Effects on ILC Like Lattice | 4491 |
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It is well known that insertion of a coupler into a RF cavity breaks the rotational symmetry of the cavity, resulting in an asymmetric field. This asymmetric field results in a transverse RF Kick. This RF kick transversely offsets the bunch from the nominal axis & it depends on the longitudinal position of the particle in the bunch. Also, insertion of coupler generates short range transverse wake field which is independent from the transverse offset of the particle. These effects cause emittance dilution and it is thus important to study their behavior & possible correction mechanisms. These coupler effects, i.e. coupler's RF kick & coupler's wake field are implemented in a beam dynamics program, Lucretia. Simulations are performed for main linac & bunch compressor of International Linear Collider (ILC) like lattices. Results are compared with Placet results & a good agreement has been achieved. |
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| THPD048 | First High-gradient Tests of the Single-cell SC Cavity with the Feedback Waveguide | 4390 |
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Use of a superconducting travelling wave accelerating (STWA) structure with a small phase advance per cell rather than a standing wave structure may provide a significant increase in the accelerating gradient in the ILC linac. For the same surface electric and magnetic fields the STWA achieves an accelerating gradient 1.2 larger than TESLA-like standing wave cavities. In addition, the STWA allows longer acceleration cavities, reducing the number of gaps between them. However, the STWA structure requires a SC feedback waveguide to return the few hundreds of MW of circulating RF power from the structure output to the structure input. A test single-cell cavity with feedback was designed and manufactured to demonstrate the possibility of a proper processing to achieve a high accelerating gradient. The first results of high-gradient tests of a prototype 1.3 GHz single-cell cavity with feedback waveguide will be presented. |