• R.H.A. Farias, F. Arroyo, E. Hayashi, L.H. Oliveira, C. Pardine, C. Rodrigues, F. Santiago de Oliveira, P.F. Tavares
  LNLS, Campinas

In November 2010, LNLS plans to replace the two 50 kW UHF klystron valves which currently provides power to the RF cavities installed in the storage ring. Thanks to a close collaboration with the Syncrotron Soleil started in 1999, LNLS adapted the characteristics of the French project to 476 MHz. The choice of the transistor, the design of the combiners and details on power supplies will be reported, as well as the power tests performed with the two amplifiers using a resistive load.

• V. Vogel, A. Cherepenko, S. Choroba, J. Hartung
  DESY, Hamburg
• P.A. Bak, N. Evmenova, A.A. Korepanov
  BINP SB RAS, Novosibirsk

For the European XFEL project horizontal multi-beam klystrons will be installed in the XFEL tunnel and will be connected to the double tank pulse transformers. Both, the klystron and pulse transformer need for the normal operation to be filled with oil. To avoid the possible oil leakage during connection of the klystron and transformer tank inside tunnel, the connection module (CM) was proposed. The CM will be mounted on the support platform of the klystron and through the tube socket connected to the guns electrodes outside of the tunnel and will transported to the tunnel together with klystron. The connection to the pulse transformer tank will be done only with HV cable, because the CM has inside it the filament transformer. To reduce the weight and volume of the oil the design of filament transformer was done as high frequency coaxial one with coupling factor of 0.58 and working frequency about 1 kHz. The CM has the built-in current and voltage monitors. In this paper we give an overview about design and test result of the CM together with klystron.

• S. Fukuda, M. Akemoto, D.A. Arakawa, H. Honma, H. Katagiri, S. Matsumoto, T. Matsumoto, S. Michizono, T. Miura, H. Nakajima, K. Nakao, S. Sakanaka, T. Shidara, T. Takahashi, Y. Yano, M. Yoshida
  KEK, Ibaraki

ERL (Energy Recovery Linac) of 5GeV energy is a future plan in KEK and in order to study the technical feasibility, construction of a compact ERL machine (cERL) is considered. Beam energy and current of cERL are 245MeV and 100mA, respectively. As 1.3 GHz frequency and super conducting cavity are chosen for the RF system, similar technology with KEK STF is employed. From 2008, KEK started the preparation of cERL and one RF unit of injector linac is introduced in this fiscal 2009. A new cw klystron of 300kW out put power, 150kW Y-type circulator and high power water load were developed in FY2009. DC power supply was under manufacturing. Preliminary test of HLRF and the high power couplers are scheduled in the Photon Factory site by making use of the old DC power supply. For main accelerator, we also introduced a 30kW IOT and a 35kW klystron and a DC power supply. At the same time, cERL is determined to be constructed in the East Counter Hall in KEK and the design layout is preceded. In this paper, the recent RF source development of cERL is described. Layout of the east counter hall, where cERL is constructed, is progressed and shown in this report.

• M. Yoshida, S. Fukuda
  KEK, Ibaraki
• H. Asano, M. Kubosaki, Y. Moriguchi
  Mitsubishi Electric Corp., Communication Systems Center, Amagasaki City, Hyogo

The L-band inductive output tube (IOT) without trolly was developed to operate under higher applied voltage. The operation frequency of conventional IOTs is tuned using its trolly. This mechanism is based on the lower frequency IOT. However it causes less insulation voltage of the ceramics since the electric insulation oil is not available for its trolly and the length of the insulation ceramics is limited because it is a part of the resonant cavity. In case of IOTs, it is important to increase the applied voltage for higher output power since the grid gap is very narrow and its area cannot be increased to keep the gain. Thus we developed an IOT which has a longer insulating ceramic and the input cavity is filled with vacuum to use the electric insulation oil. Further the dielectric waveguide can solve to feed the input microwave to the cathode grid without trolly. These new features of the IOT is very effective for the fixed frequency application such as the accelerator, for example the energy recovery linac. The design and the experimental results will be presented in this report.

• A. Kanareykin
  Euclid TechLabs, LLC, Solon, Ohio
• S. Kazakov
  KEK, Ibaraki
• A.B. Kozyrev
  LETI, Saint-Petersburg
• E. Nenasheva
  Ceramics Ltd., St. Petersburg
• V.P. Yakovlev
  Fermilab, Batavia

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.
** A.Kozyrev et al Applied Physics Letters,v.95,p.012908,(2009).

• K.M. Schirm, S. Curt, S. Döbert, G. McMonagle, G. Rossat, I. Syratchev, L. Timeo
  CERN, Geneva
• A.A. Haase, A. Jensen, E.N. Jongewaard, C.D. Nantista, D.W. Sprehn, A.E. Vlieks
  SLAC, Menlo Park, California
• A. Hamdi, F. Peauger
  CEA, Gif-sur-Yvette
• S.V. Kuzikov, A.A. Vikharev
  IAP/RAS, Nizhny Novgorod

The CLIC RF frequency has been changed in 2008 from the initial 30 GHz to the European X-band 11.9942 GHz permitting beam independent power production using klystrons for CLIC accelerating structure testing. A design and fabrication contract for five klystrons at that frequency has been signed by different parties with SLAC. France (CEA Saclay) is contributing a solid state modulator purchased in industry to the CLIC study. RF pulses over 120 MW peak at 230 ns length will be obtained by using a novel SLED I type pulse compression scheme designed and fabricated in Nizhny Novgorod, Russia. The X-band power test stand has been installed in the CLIC Test Facility CTF3 for independent structure and component testing in a bunker, but allowing, in a later stage, for powering RF components in the CTF3 beam lines. The design of the facility, results from commissioning of the RF power source and the performance of the Test Facility are reported.

• T.-C. Yu, L.-H. Chang, M.-C. Lin, Ch. Wang, M.-S. Yeh
  NSRRC, Hsinchu

The RF power source using solid-state amplifier for accelerator application has become popular in recent years. The amplifiers array using power divider and power combiner could obtain equivalent power level as those using klystron or IOT. Such solid-state RF power source also has the advantage of easy maintenance, low cost, low DC power voltage and high flexibility. The development of solid-state power amplifier module at 499.65 MHz using the latest RF power chip has been built to have the power level of 900 Watts with above 60% efficiency of single power module. The more power that one module can provide, the less number of modules would be required under the same total output power of amplifiers array. Thus, the construction of a transmitter by solid-state technique for RF system would be less complex for easy maintenance.

• A.J. Moss, P.A. Corlett, P.A. McIntosh, J.F. Orrett, A.E. Wheelhouse
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• C.J. White
  STFC/DL, Daresbury, Warrington, Cheshire

The Muon Ionisation Cooling Experiment (MICE) is being constructed at Rutherford Appleton Laboratory in the UK. A muon beam will be cooled through a process of absorption using hydrogen absorbers and acceleration using 200MHz copper RF cavities. This paper describes the RF power source used to accelerate the muon beam, testing of the high voltage power supplies and amplifiers to date and progress on the RF distribution scheme to the accelerating cavities.

• A.E. Wheelhouse, R.K. Buckley, P. Goudket, P.A. McIntosh, A.J. Moss, J.F. Orrett
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire

The RF system on EMMA (Electron Model for Many Applications), the world's first Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) accelerator is presently being installed and commissioned at Daresbury Laboratory. The RF system is required to provide precise amplitude and phase control to each of the 19 identical normal conducting, 1.3 GHz RF cavities which provide the acceleration of the electron beam from 10 MeV to 20 MeV. The system incorporates a high power RF system, which includes a single 100 kW Inductive Output Tube (IOT), a unique RF distribution system and a low level RF (LLRF) control system. The design of the RF system and the commissioning progress to date is presented.

• Y. Xu
  Lancaster University, Lancaster
• R. Seviour
  Cockcroft Institute, Lancaster University, Lancaster

2D Photonic crystals (PC) with defects can act as standing-wave resonators, which offer benefit of high mode selectivity for building novel RF sources. We introduce our work on designing two-cavity single-beam and multi-beam klystrons using triangular lattice metallic PCs. We present the cold test results of the stub-coupled single-beam structure, which show that at resonance a very low reflection can be obtained, and the waves are well confined. We also present bead-pull measurement results of field strengths in the defect, using modified perturbation equation for small unit dielectric cylinder, which are in very good agreement to numerical results. A 6-beam klystron cavity is designed as a 6-coupled-defect structure with a central stub, which only couples to the in-phase mode at the lowest frequency. Finally, we present a feasibility discussion of using this multi-defect PC structure to construct an integrated klystron-accelerator cavity, along with numerical results showing a peak acceleration field of 22MV/m can be achieved.

• M. Popovic, A. Moretti
  Fermilab, Batavia
• A. Dudas, R.P. Johnson, M.L. Neubauer, R. Sah
  Muons, Inc, Batavia

Typically, high power sources for accelerator applications are multi-megawatt microwave tubes that may be combined together to form ultra-high-power localized power stations. The RF power is then distributed to multiple strings of cavities through high power waveguide systems which are problematic in terms of expense, efficiency, and reliability. Magnetrons are the lowest cost microwave source in dollars/kW, and they have the highest efficiency (typically greater than 85%). However, the frequency stability and phase stability of magnetrons are not adequate, when magnetrons are used as power sources for accelerators. Novel variable frequency cavity techniques have been developed which will be utilized to phase and frequency lock magnetrons, allowing their use for either individual cavities, or cavity strings. Ferrite or YIG (Yttrium Iron Garnet) materials will be attached in the regions of high magnetic field of radial-vaned, π−mode structures of a selected ordinary magnetron. A variable external magnetic field that is orthogonal to the magnetic RF field of the magnetron will surround the magnetron to vary the permeability of the ferrite or YIG material.

• M.L. Neubauer, A. Dudas, R. Sah
  Muons, Inc, Batavia
• M. Borland, R. Nassiri
  ANL, Argonne

An extremely low emittance RF gun is being designed for the X-ray Free Electron Laser Oscillator (XFEL-O), which is now being proposed by ANL. An adjustable coupling factor for this gun is very desirable for providing operational flexibility. What is required is a fundamental RF power coupler (FPC), adjustable in situ, that can operate at 100 MHz and 200 kW CW. If rotational motion is used in the adjustable coupler, it is usually necessary to break the vacuum between the coupler and the RF cavity, thereby risking prolonged down-times and the introduction of contaminants into the vacuum system. We propose a novel system for adjusting the coupling coefficient of coaxial couplers to allow for individual control and adjustments to the RF fields under different beam loading scenarios. The RF coupler has no movable parts and relies on a ferrite tuner assembly, coax TEE, and double windows to provide a VSWR of better than 1.05:1 and a bandwidth of at least 8 MHz at 1.15:1. The ferrite tuner assembly on the stub end of the coax TEE uses an applied DC magnetic field to change the Qext and the RF coupling coefficient, β, between the RF input and the cavity.

• T.A. Treado, P. Brown, S. Evans, M.E. Marks
  CPI, Beverley, Massachusetts

The VIL409 Heatwave IOT-based RF amplifier was designed to meet the requirements of the EMMA accelerator at the Daresbury Laboratory. The VIL409 was successfully commissioned in September 2009. The VIL409 provides up to 90 kW RF output power ver a 5.5 MHz bandwidth centered at 1.3 GHz. It operates at a fixed 1.6 millisecond pulse at up to 20 Hz. Within limits, the user has control of the IOT beam voltage and the IOT grid bias voltage. Normal operation is to achieve smooth control of the output via the LLRF input alone. The IOT grid may be pulsed or operated at a constant voltage; pulsing achieves greatly enhanced energy efficiency. The VIL409 has an embedded processor that controls all internal functions of the amplifier system and interfaces directly to the EPICS control system. The embedded controller provides real-time pulse data to EPICS and operates slow-moving interlocks. Safety and IOT-protective interlocks are hard-wire circuits which operate in the microsecond timeframe. The VIL409 can be operated locally or controlled remotely on the EPICS controls network. This paper describes the VIL409 high power RF amplifier system.

• J.T.M. Lyles, S. Archuletta, N.K. Bultman, Z.C. Chen, J. Davis, A.C. Naranjo, D. Rees, G. M. Sandoval, Jr., D.S. Warren
  LANL, Los Alamos, New Mexico
• D. Baca, R.E. Bratton, R.D. Summers
  Compa Industries, Inc., Los Alamos, New Mexico

An major upgrade is replacing much of the 40 year-old proton drift tube linac RF system with new components at Los Alamos Neutron Science Center (LANSCE). When installed for the LANSCE-R project, the new system will reduce the total number of electron power tubes from twenty-four to eight in the RF powerplant. A new 200 MHz high power cavity amplifier has been developed at LANSCE. This 3.2 MW final power amplifier (FPA) uses a Thales TH628 Diacrode, a state-of-the-art tetrode that eliminates the large anode modulator of the triode-based FPA that has been in use for four decades. Drive power for the FPA is provided by a new tetrode intermediate power amplifier and a solid-state driver stage. The new system has sufficient duty-factor capability to allow LANSCE to return to 1 MW beam operation. Prototype RF power amplifiers have been designed, fabricated, and assembled and are being tested. High voltage DC power became available through innovative re-engineering of an installed system. Details of the electrical and mechanical design of the FPA and ancillary systems are discussed. Power test results have validated the design and construction of this very high power amplifier system.

• C. Adolphsen
  SLAC, Menlo Park, California

The Linac Group at SLAC is actively pursuing a broad range of R&D to improve the reliability and reduce the cost of the L-band (1.3 GHz) rf system proposed for the ILC linacs. Current activities include the long-term evaluation of a 120 kV Marx Modulator driving a 10 MW Multi-Beam Klystron, design of a second-generation Marx Modulator, testing of a sheet-beam gun and beam transport system for a klystron, construction of an rf distribution system with remotely-adjustable power tap-offs, and development of a system to combine the power from many klystrons in low-loss circular waveguide where it would be tapped-off periodically to power groups of cavities. This paper surveys progress during the past few years.

• D.W. Sprehn, A.A. Haase, A. Jensen, E.N. Jongewaard, C.D. Nantista, A.E. Vlieks
  SLAC, Menlo Park, California

A 12 GHz 50MW X-band klystron is under development at the SLAC National Accelerator Laboratory Klystron Department. The klystron will be fabricated to support programs currently underway at three European Labs; CERN, PSI, and INFN Trieste. The choice of frequency selection was due to the CLIC RF frequency changing from 30 GHz to the European X-band frequency of 11.9942 GHz in 2008. Since the Klystron Department currently builds 50MW klystrons at 11.424 GHz known collectively as the XL4 klystrons, it was deemed cost-effective to utilize many XL4 components by leaving the gun, electron beam transport, solenoid magnet and collector unchanged. To realize the rf parameters required, the rf cavities and rf output hardware were necessarily altered. Some improvements to the rf design have been made to reduce operating gradients and increase reliability. Changes in the multi-cell output structure, waveguide components, and the window will be discussed along with testing of the devices. Five klystrons known as XL5 klystrons are scheduled for production over the next two years.

• D.W. Sprehn, A.A. Haase, A. Jensen, E.N. Jongewaard, D.W. Martin
  SLAC, Menlo Park, California

The SLAC National Accelerator Laboratory Klystron Department is developing a 10 MW, 5 Hz, 1.6 ms, 1.3 GHz plug-compatible Sheet-Beam Klystron as a less expensive and more compact alternative to the ILC baseline Multiple-Beam Klystron. Earlier this year a beam tester was constructed and began test. Device fabrication issues have complicated the analysis of the data collected from an intercepting cup for making beam quality measurements of the 130 A, 40-to-1 aspect ratio beam. Since the goal of the beam tester is to confirm 3d beam simulations it was necessary to rebuild the device in order to mitigate unwanted effects due to imperfect focusing construction. Measurements are underway to verify the results of this latest incarnation. Measurement will then be made of the beam after transporting through a drift tube and magnetic focusing system. In the klystron design, a TE oscillation was discovered during long simulation runs of the entire device which has since prompted two design changes to eliminate the beam disruption. The general theory of operation, the design choices made, and results of testing of these various devices will be discussed.

• H. Wang, G.K. Davis, R.A. Rimmer
  JLAB, Newport News, Virginia
• G. Burt, R.G. Carter, A.C. Dexter, M.I. Tahir
  Cockcroft Institute, Lancaster University, Lancaster

The use of an injection locked CW magnetron to drive a 2.45 GHz superconducting RF cavity has been successfully demonstrated. With a locking power less than -27 dB with respect to the output and with a phase control system acting on the locking signal, cavity phase was accurately controlled for hours at a time without loss of lock whilst suppressing microphonics. The phase control accuracy achieved was 0.8o r.m.s. The main contributing disturbance limiting ultimate phase control was power supply ripple from the low specification switch mode power supply used for the experiment.