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Paper Title Other Keywords Page
TU201 Linac R&D for the ILC Technical Design Report linac, cryomodule, linear-collider, cavity 359
  • M.C. Ross
    Fermilab, Batavia

The International Linear Collider (ILC) Technical Design Report (TDR) is scheduled for publication in 2012. The TDR will include an updated ILC baseline technical design description, results from critical R&D programs in support of key parameter choices, and one or more models for a Project Implementation Plan with an associated value estimate. The focus of linac R&D is to:

  1. achieve the specified superconducting rf cavity accelerating gradient of 35 MV/m with a corresponding production yield,
  2. design and test cryomodule assemblies that include "plug-compatible" sub-components with specified interfaces, and
  3. demonstrate system performance with nominal ILC high intensity beams.
In keeping with the international nature of the project, R&D is underway at ILC partner institutions with results and infrastructure that are shared throughout the project effort. This paper describes the technical challenges to be addressed and summarizes ongoing activities and plans.


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TUP021 Digitally Controlled High Availability Power Supply power-supply, controls, linear-collider, diagnostics 437
  • D.J. MacNair
    SLAC, Menlo Park, California

Funding: US DOE
This paper reports the design and test results on novel topology, high-efficiency, and low operating temperature, 1,320-watt power modules for high availability power supplies. The modules permit parallel operation for N+1 redundancy with hot swap capability. An embedded DSP provides intelligent start-up and shutdown, output regulation, general control and fault detection. PWM modules in the DSP drive the FET switches at 20 to 100 kHz. The DSP also ensures current sharing between modules, synchronized switching, and soft start up for hot swapping. The module voltage and current have dedicated ADCs (>200 kS/sec) to provide pulse-by-pulse output control. A Dual CAN bus interface provides for low cost redundant control paths. Over-rated module components provide high reliability and high efficiency at full load. Low on-resistance FETs replace conventional diodes in the buck regulator. Saturable inductors limit the FET reverse diode current during switching. The modules operate in a two-quadrant mode, allowing bipolar output from complimentary module groups. Controllable, low resistance FETs at the input and output provide fault isolation and allow module hot swapping.

TUP048 Identifying Jitter Sources in the LCLS Linac quadrupole, linac, klystron, pick-up 506
  • F.-J. Decker, R. Akre, A. Brachmann, W.S. Colocho, Y.T. Ding, D. Dowell, P. Emma, J.C. Frisch, A. Gilevich, G.R. Hays, P. Hering, Z. Huang, R.H. Iverson, K.D. Kotturi, A. Krasnykh, C. Limborg-Deprey, H. Loos, S. Molloy, H.-D. Nuhn, D.F. Ratner, J.L. Turner, J.J. Welch, W.E. White, J. Wu
    SLAC, Menlo Park, California

The beam stability for the Linac Coherent Light Source (LCLS) Free-Electron Laser (FEL) at Stanford Linear Accelerator Center (SLAC) are critical for X-Ray power, pointing, and timing stability. Studies of the transverse, longitudinal, and intensity stability of the electron beam are presented. Identifying these sources by different methods like correlations, frequency spectrum analysis and other methods is critical for finally eliminating or reducing them.


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TUP055 Optimum Frequency and Gradient for the CLIC Main Linac Accelerating Structure linac, luminosity, wakefield, accelerating-gradient 527
  • A. Grudiev, H.-H. Braun, D. Schulte, W. Wuensch
    CERN, Geneva

Recently the CLIC study has changed the operating frequency and accelerating gradient of the main linac from 30 GHz and 150 MV/m to 12 GHz and 100 MV/m, respectively. This major change of parameters has been driven by the results from a novel main linac optimization procedure. The procedure allows simultaneous optimization of operating frequency, accelerating gradient, and many other parameters of CLIC main linac. It takes into account both beam dynamics (BD) and high power rf constraints. BD constraints are related to emittance growth due to short- and long-range transverse wakefields. Rf constraints are related to rf breakdown and pulsed surface heating of the accelerating structure. The optimization figure of merit includes the power efficiency, measured as a ratio of luminosity to the input power as well as a quantity proportional to investment cost.

THP023 Crab Cavities for Linear Colliders cavity, dipole, beam-loading, linac 830
  • G. Burt, P.K. Ambattu, R.G. Carter, A.C. Dexter, M.I. Tahir
    Cockcroft Institute, Lancaster University, Lancaster
  • C. Adolphsen, Z. Li, A. Seryi, L. Xiao
    SLAC, Menlo Park, California
  • C.D. Beard, D.M. Dykes, P. Goudket, A. Kalinin, L. Ma, P.A. McIntosh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • L. Bellantoni, B. Chase, M. Church, T.N. Khabiboulline
    Fermilab, Batavia
  • R.M. Jones
    UMAN, Manchester
  • A. Latina, D. Schulte
    CERN, Geneva

Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favours a 3.9 GHz superconducting, multi-cell cavity as the ILC solution, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are special issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.

THP053 The Status of Nextef; The X-band Test Facility in KEK klystron, linear-collider, controls, status 906
  • S. Matsumoto, M. Akemoto, S. Fukuda, T. Higo, N. Kudoh, H. Matsushita, H. Nakajima, T. Shidara, K. Yokoyama, M. Yoshida
    KEK, Ibaraki

Nextef is a new X-band (11.4GHz) test facility in KEK. All of the key devices of this facility are from our old X-band Test Facility(XTF). By combining the power from two klystrons, 100 MW maximum X-band rf power is produced and 75MW is available in the bunker where the high power test of the high gradient accelerator structures will be done. The commissioning of the facility for the structure testing has almost done. The status of the facilityis is reported.

THP061 High Power Test of a Low Group Velocity X-Band Accelerator Structure for CLIC damping, vacuum, HOM, luminosity 930
  • S. Döbert, A. Grudiev, G. Riddone, M. Taborelli, W. Wuensch, R. Zennaro
    CERN, Geneva
  • C. Adolphsen, V.A. Dolgashev, L. Laurent, J.R. Lewandowski, S.G. Tantawi, F. Wang, J.W. Wang
    SLAC, Menlo Park, California
  • S. Fukuda, Y. Higashi, T. Higo, S. Matsumoto, K. Ueno, K. Yokoyama
    KEK, Ibaraki

In recent years evidence has been found that the maximum sustainable gradient in an accelerating structure depends on the rf power flow through the structure. The CLIC study group consequently designed a new prototype structure for CLIC with a very low group velocity, input power and average aperture (a/λ = 0.12). The 18 cell structure has a group velocity of 2.4% at the entrance and 1% at the last cell. Several of these structures have been made in collaboration between KEK, SLAC and CERN. A total of five brazed-disk structures and two quadrant structures have been made. The high power results of some of these structures are presented. The first KEK/SLAC built structure reached an unloaded gradient in excess of 100 MV/m at a pulse length of 230 ns with a breakdown rate below 10-6. The high-power testing was done using the NLCTA facility at SLAC.

THP090 Marx Bank Technology for Accelerators and Colliders high-voltage, controls, impedance, diagnostics 1002
  • J.A. Casey, F.O. Arntz, R. Ciprian, M.P.J. Gaudreau, M.K. Kempkes, I. Roth
    Diversified Technologies, Inc., Bedford, Massachusetts

Funding: U.S. Department of Energy SBIR Program
Diversified Technologies, Inc. (DTI) has developed high power, solid-state Marx Bank designs for a range of accelerator and collider designs. We estimate the Marx topology can deliver equivalent performance to conventional designs, while reducing acquisition costs by 25-50%. In this paper DTI will describe the application of Marx based technology to two different designs: a long-pulse ILC focused design (140 kV, 160 A, 1.5 ms), and a short-pulse design (500 kV, 265 A, 3 us). These designs span the known requirements for future accelerator modulators. For the ILC design, the primary challenge is minimizing the overall size and cost of the storage capacitors in the modulator. For the short-pulse design, the primary challenge is high speed operation, to limit the energy lost in the pulse rise-time while providing a very tight (± 3%) voltage flattop. Each design demands unique choices in components and controls, including the use of electrolytic capacitors in the ILC Marx design. This paper will review recent progress in the development and testing of both of these prototype Marx designs, being built under two separate DOE Phase II SBIR grants.