H. Deruyter

Bio: H. Deruyter is an academic researcher from Stanford University. The author has contributed to research in topics: Particle accelerator & Linear particle accelerator. The author has an hindex of 9, co-authored 15 publications receiving 182 citations.

The Next Linear Collider Test Accelerator

Abstract: During the past several years, there has been tremendous progress on the development of the RF system and accelerating structures for a Next Linear Collider (NLC). Developments include high-power klystrons, RF pulse compression systems and damped/detuned accelerator structures to reduce wakefields. In order to integrate these separate development efforts into an actual X-band accelerator capable of accelerating the electron beams necessary for an NLC, we are building an NLC Test Accelerator (NLCTA). The goal of the NLCTA is to bring together all elements of the entire accelerating system by constructing and reliably operating an engineered model of a high-gradient linac suitable for the NLC. The NLCTA will serve as a testbed as the design of the NLC evolves. In addition to testing the RF acceleration system, the NLCTA is designed to address many questions related to the dynamics of the beam during acceleration. In this paper, we will report on the status of the design, component development, and construction of the NLC Test Accelerator. >

Accelerator structure R&D for linear colliders

Abstract: For more than ten years, we have been working on R&D for X-band accelerator structures for the JLC/NLC linear collider. Several types of Detuned (DS) and Damped Detuned Structures (DDS) have been successfully designed and fabricated. They have been experimentally tested at both low power and high power to characterize their mechanical and electrical properties. Recently we started developing a new type of damped detuned structure with optimized round-shaped cavities (RDDS). This paper discusses the special specifications, design methods, fabrication procedures, measurement technologies, and anticipated future improvements for all these structures.

Flower-petal mode converter for NLC

Abstract: It is important to minimize power loss in the waveguide system connecting klystron, pulse-compressor, and accelerator in an X-Band NLC. However, existing designs of klystron output cavity circuits and accelerator input couplers utilize rectangular waveguide which has relatively high transmission loss. It is therefore necessary to convert to and from the low-loss mode in circular waveguide at each end of the system. A description is given of development work on high-power, high-vacuum 'flower-petal' transducers, which convert the TE/sub 10/ mode in rectangular guide to the TE/sub 01/ mode in circular guide. A three-port modification of the flower petal device, which can be used as either a power combiner at the klystron or a power divider at the accelerator is also described. >

High Gradient Tests of SLAC Linear Collider Accelerator Structures

Abstract: This paper describes the current SLAC R&D program to develop room tem~rature accelerator structures for the Next Linear Collider (NLC). me s~ctures are designd to operate at 11.4 GHz at an accelerating gradient in the range of 50 to 100 MV/m. In the past year a 26 cm constant-impedance traveling-wave section, a 75 cm constant-im~dmce travelingwave section, and a 1.8 m traveling-wave section with detuned deflecting modes have been high-power tested. The paper presents a brief description of the RF test setup, the design and manufacturing details of the structures, and a discussion of test results includlng field emission, RF processing, dark current spwtrum and RF breakdown. Experimental Setup ., Accelerator structures descriti in this paper were dl testi in the Accelerator Structure Test Area (ASTA) facility located

Accelerator Structure Development for NLC

Abstract: In the program of work directed towards the development of an X-Band Next Linear Collider accelerator structure, two different test accelerator sections have been completed, and a third is being fabricated. The first is a simple 30-cell constant-impedance section in which no special attention was given to surface finish, pumping, and alignment. The second is an 86-cell section in which the cells were precision diamond-turned by Texas Instruments Inc. The structure has internal water-cooling and vacuum pumping manifolds. Some design details are given for the third section, which is a 206-cell structure with cavities dimensioned to give a Gaussian distribution of dipole mode frequencies. It has conventional machining surface finishes and external water and pumping manifolds. Component design, fabrication, and assembly brazing are described for the first two experimental sections. >

Field emission and RF breakdown in high gradient room temperature linac structures

Abstract: The purpose of this article is to serve as a tutorial review on the subject of field emission and rf breakdown in high-gradient room-temperature accelerator structures and associated devices. The need to understand and control these two phenomena has become increasingly important because of the prospect of using high-gradient structures in future linear colliders. Electron field emission creates so-called dark current which parasitically absorbs rf energy, causes radiation, backgrounds, and possibly wakefields; it seems to be the precursor of rf breakdown, possibly in combination with local outgassing and plasma formation. In turn, rf breakdown limits the operation of accelerators and can cause irreversible damage to their physical structures. Research on these topics is interesting and challenging because it involves a mixture of disciplines such as surface physics, metallurgy, fabrication technologies, microwaves, beam dynamics and plasmas. This review consists of four parts: (1) field emission under dc, enhanced and rf conditions; (2) experimental set-ups; (3) prebreakdown stage--dark current and radiation; (4) experimental observations and analysis of rf breakdown. The review ends with conclusions and an outline of work that remains to be done.

High-gradient electron accelerator powered by a relativisitic klystron.

Abstract: We have used relativistic klystron technology to extract 290 MW of peak power at 11.4 GHz from an induction linac beam, and to power a short 11.4-GHz high-gradient accelerator. We have measured rf phase stability, field emission, and the momentum spectrum of an accelerated electron beam. An average accelerating gradient of 84 MV/m has been achieved with 80 MW of relativistic klystron power.

Active high-power RF pulse compression using optically switched resonant delay lines

Abstract: We present the design and a proof of principle experimental results of an optically controlled high-power RP pulse-compression system. In principle, the design should handle a few hundreds of megawatts of power at X-band. The system is based on the switched resonant delay-line theory [1]. It employs resonant delay lines as a means of storing RF energy. The coupling to the lines is optimized for maximum energy storage during the charging phase. To discharge the lines, a high-power microwave switch increases the coupling to the lines just before the start of the output pulse. The high-power microwave switch required for this system is realized using optical excitation of an electron-hole plasma layer on the surface of a pure silicon wafer. The switch is designed to operate in the TE/sub 01/ mode in a circular waveguide to avoid the edge effects present at the interface between the silicon wafer and the supporting waveguide; thus, enhancing its power handling capability.

Computer Determination of the External $Q$ and Resonant Frequency of Waveguide Loaded Cavities

Abstract: A new method is proposed for determining the Qext of a cavity coupled to a waveguide that is well suited to integration with computer methods for determination of cavity resonant frequencies. It is related to, but distinct from, Slater's method, which has recently been applied in the same context. Application of the method to a set of waveguide models with comparison to analytic results is presented. An application to a damped accelerator cavity structure using MAFIA-determined resonant frequencies is also given.

Commissioning experience and beam physics measurements at the SwissFEL Injector Test Facility

Abstract: The SwissFEL Injector Test Facility operated at the Paul Scherrer Institute between 2010 and 2014, serving as a pilot plant and testbed for the development and realization of SwissFEL, the X-ray Free-Electron Laser facility under construction at the same institute. The test facility consisted of a laser-driven rf electron gun followed by an S-band booster linac, a magnetic bunch compression chicane and a diagnostic section including a transverse deflecting rf cavity. It delivered electron bunches of up to 200 pC charge and up to 250 MeV beam energy at a repetition rate of 10 Hz. The measurements performed at the test facility not only demonstrated the beam parameters required to drive the first stage of an FEL facility, but also led to significant advances in instrumentation technologies, beam characterization methods and the generation, transport and compression of ultra-low-emittance beams. We give a comprehensive overview of the commissioning experience of the principal subsystems and the beam physics measurements performed during the operation of the test facility, including the results of the test of an in-vacuum undulator prototype generating radiation in the vacuum ultraviolet and optical range.