Download or read book Experimental Studies of W band Accelerator Structures at High Field written by Marc Edward Hill and published by . This book was released on 2000 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Studies of W Band Accelerator Structures at High Field written by and published by . This book was released on 2001 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: A high-gradient electron accelerator is desired for high-energy physics research, where frequency scalings of breakdown and trapping of itinerant beamline particles dictates operation of the accelerator at short wavelengths. The first results of design and test of a high-gradient mm-wave linac with an operating frequency at 91.392 GHz (W-band) are presented. A novel approach to particle acceleration is presented employing a planar, dielectric lined waveguide used for particle acceleration. The traveling wave fields in the planar dielectric accelerator (PDA) are analyzed for an idealized structure, along with a circuit equivalent model used for understanding the structure as a microwave circuit. Along with the W-band accelerator structures, other components designed and tested are high power rf windows, high power attenuators, and a high power squeeze-type phase shifter. The design of the accelerator and its components where eased with the aide of numerical simulations using a finite-difference electromagnetic field solver. Manufacturing considerations of the small, delicate mm-wave components and the steps taken to reach a robust fabrication process are detailed. These devices were characterized under low power using a two-port vector network analyzer to verify tune and match, including measurements of the structures' fields using a bead-pull. The measurements are compared with theory throughout. Addition studies of the W-band structures were performed under high power utilizing a 11.424 GHz electron linac as a current source. Test results include W-band power levels of 200 kW, corresponding to fields in the PDA of over 20 MV/m, a higher gradient than any collider. Planar accelerator devices naturally have an rf quadrupole component of the accelerating field. Presented for the first time are the measurements of this effect.

Download or read book Experimental Studies of Novel Accelerator Structures at 11 GHz and 17 GHz written by Brian James Munroe and published by . This book was released on 2015 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photonic band-gap (PBG) structures are promising candidates for electron accelerators capable of high-gradient operation because they have the inherent damping of high order modes required to avoid beam breakup due to instabilities. A key challenge for PBG structures is high-gradient operation without structure damage due to rf-field-induced breakdowns. This thesis reports theoretical results on the design of PBG structures and the generation of wakefields in such structures. It also reports experimental results on PBG structure breakdown testing at high power at both 11 and 17 GHz. A single-cell photonic band-gap (PBG) structure was designed with an inner row of elliptical rods (PBG-E) to reduce ohmic heating relative to a round-rod structure. The PBG-E structure was built and tested at high power at a 60 Hz repetition rate at X-Band (11.424 GHz) at the SLAC accelerator test stand, achieving a gradient of 128 MV/m at a breakdown probability of 3.6 x 10-3 per pulse per meter at a pulse length of 150 ns. The PBG-E structure showed major improvement in breakdown rate relative to a round-rod PBG structure designed at MIT and previously tested at SLAC. A test stand was designed and built at MIT for testing single-cell structures at 17.1 GHz, a frequency 50% higher than the SLAC frequency. This test stand provides comparable diagnostics to those used at SLAC, adding optical diagnostic access which can be used for open PBG structures. A conventional disc-loaded waveguide structure, MIT-DLWG, was tested at MIT at up to a 2 Hz repetition rate. This structure reached a maximum gradient of 87 MV/m at a breakdown probability of 1.19 x 10-1 per pulse per meter. A round-rod PBG structure, MIT-PBG-2, has also been tested at MIT at up to a 2 Hz repetition rate and 100 ns pulse length, demonstrating operation up to 89 MV/rn at a breakdown probability of 1.09 x 10-1 per pulse per meter. These test results show that a PBG structure can simultaneously operate at high gradients and low breakdown probability, while also providing wakefield damping. This makes PBG structures viable candidates for future collider applications.

Download or read book Experimental Studies of Hybrid Photonic Band Gap Accelerator Structures written by JieXi Zhang and published by . This book was released on 2016 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis reports the first high power tests of a hybrid photonic band gap (PBG) accelerator structure. PBG structures can support a single electromagnetic mode, thus damping higher-order modes (HOMs) generated by wakefields. We have designed, built and successfully tested a 17.14 GHz hybrid PBG (HPBG) structure containing both dielectric and metallic elements. Dielectric elements have low loss and the potential to survive high surface electromagnetic fields. The HPBG structure was constructed as a triangular lattice array with sapphire rods inside and copper rods outside sandwiched between copper plates. The lattice parameter and the rod pattern were adjusted to excite a high-Q TM0 2 mode and to suppress HOMs. This overmoded operation is a unique and novel feature of the hybrid design. The design included the birefringence of sapphire. Simulations showed relatively high surface fields at the triple point where sapphire, copper and vacuum meet as well as in any gaps between components in the clamped assembly. Three structures were tested with later structures designed to sequentially reduce the surface electric field. The third structure used sapphire rods with pin extensions at each end and obtained the highest gradient of 19 MV/m, corresponding to a surface E field of 78 MV/m, with a breakdown probability of 5 x 10 1 /pulse/m in 45-ns pulses. Operation above 20 MV/m gradient led to runaway breakdowns with extensive light emission and eventual damage. For all three structures, multipactor light emission was observed at gradients well below the breakdown threshold. Breakdown damage was found at the triple point where surface fields peaked. The deposition of copper onto sapphire resulting from breakdowns might eventually degrade the cavity quality. This research indicated that multipactor triggered at the triple point limited the operational gradient of the hybrid structure. These experiments represent the first high power tests of a hybrid PBG structure. The gradient achieved of 19 MV/m is the highest achieved with a dielectric structure. The gradient was found to be limited by multipactor and breakdown. The overmoded cavity with relatively large beam apertures might still find applications at high frequency or in high current transmission.

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Final Report on Development and Testing of Advanced Accelerator Structures and Technologies at 11 424 GHz written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the final report on the research program?Development and Testing of Advanced Accelerator Structures and Technologies at 11.424 GHz,? which was carried out by the Naval Research Laboratory (NRL) under Interagency Agreement DE?AI02?01ER41170 with the Department of Energy. The period covered by this report is 15 July 2010? 14 July 2013. The program included two principal tasks. Task 1 involved a study of the key physics issues related to the use of high gradient dielectric-loaded accelerating (DLA) structures in rf linear accelerators and was carried out in collaboration with Argonne National Laboratory (ANL) and Euclid Techlabs LLC. Task 2 involved a study of high power active microwave pulse compressors and was carried out in collaboration with Omega-P, Inc. and the Institute of Applied Physics of the Russian Academy of Sciences in Nizhny Novgorod. The studies under Task 1 were focused on rf-induced multipactor and breakdown in externally driven DLA structures at the 200-ns timescale. Suppression of multipactor and breakdown are essential to the practical application of dielectric structures in rf linear accelerators. The structures that were studied were developed by ANL and Euclid Techlabs and their performance was evaluated at high power in the X-band Magnicon Laboratory at NRL. Three structures were designed, fabricated, and tested, and the results analyzed in the first two years of the program: a clamped quartz traveling-wave (TW) structure, a externally copper-coated TW structure, and an externally copper-coated dielectric standing-wave (SW) structure. These structures showed that rf breakdown could be largely eliminated by eliminating dielectric joints in the structures, but that the multipactor loading was omnipresent. In the third year of the program, the focus of the program was on multipactor suppression using a strong applied axial magnetic field, as proposed by Chang et al. [C. Chang et al., J. Appl. Phys. 110, 063304 (2011).], and a successful experiment was carried out that demonstrated suppression of multipactor in the uniform-field region of a TW DLA structure. However, in accordance with theory, the multipactor was enhanced in regions of the structure with lower values of axial magnetic field. Under Task 2, there were two two-month experimental runs at NRL that were used to characterize the performance of high power two-channel dual-mode active microwave pulse compressor configurations that used electron-beam triggered switch cavities. The pulse compressors were designed and fabricated by Omega-P, Inc. and the Russian Institute of Applied Physics and tested in the Magnicon Laboratory at NRL. These pulse compressors made use of an electron beam discharge from a cylindrical knife-edged Mo cathode coated with a CVD diamond film that was driven by a?100 kV, 100 ns high voltage pulse. The electron beam was used to change the resonant frequency of the switch cavities in order to create the output microwave pulse. The compressor channels included a TE01 input and output section and a TE02 energy storage cavity, followed by a switch assembly that controlled the coupling between the TE01 and TE02 modes. In the initial state, the switch cavity was in resonance, the reflection from the cavity was out of phase, and the mode conversion was only ~2-3%, allowing the energy storage cavity to fill. When the electron beam was discharged into the switch cavity, the cavity was shifted out of resonance, causing the phase of the reflection to change by ~[pi]. As a result of the change in the reflection phase, the mode coupling in the conical taper was greatly increased, and could approach ~100%, permitting the energy storage cavity to empty in one cavity round trip time of the TE02 mode to produce a high power output pulse. The second experiment runs demonstrated a 190 MW, ~20 ns compressed pulse at 25.7 gain and ~50% efficiency, using a 7.4 MW, 1?s drive pulse from the magnicon. The success of this experiment suggests ...

Download or read book Experimental Study of Photonic Band Gap Accelerator Structures written by Roark A. Marsh and published by . This book was released on 2009 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: (cont.) No breakdown damage was observed on the iris surface, the location of peak electric field, but pulsed heating damage was observed on the inner rods, the location of magnetic fields as high as 1 MA/m. Breakdown in accelerator structures is generally understood in terms of electric field effects. PBG structure results highlight the unexpected role of magnetic fields on breakdown. The hypothesis is presented that the low level electric field on the inner rods is enhanced by pulsed heating surface damage, and causes breakdown. A new PBG structure was designed with improved pulsed heating, and will be tested. These results greatly further the understanding of advanced structures with wakefield suppression that are necessary for future colliders.

Download or read book Advances Of Accelerator Physics And Technologies written by Herwig Schopper and published by World Scientific. This book was released on 1993-03-12 with total page 765 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume, consisting of articles written by experts with international repute and long experience, reviews the state of the art of accelerator physics and technologies and the use of accelerators in research, industry and medicine. It covers a wide range of topics, from basic problems concerning the performance of circular and linear accelerators to technical issues and related fields. Also discussed are recent achievements that are of particular interest (such as RF quadrupole acceleration, ion sources and storage rings) and new technologies (such as superconductivity for magnets and RF cavities).The book will interest not only researchers and engineers in the field of accelerator development but also users of accelerators in research and industry. Moreover, teachers giving courses on accelerators and their applications will profit by learning about the most recent achievements and future possibilities.

Download or read book Progress Report on High gradient RF Studies in Copper Accelerator Structures written by and published by . This book was released on 1990 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper is a progress report on studies carried out at the Stanford Linear Accelerator Center to understand the behavior of copper accelerator structures under extremely high RF fields. Such structures are being designed for future electron-positron linear colliders. Recent studies include field emission and breakdown experiments with an S-band slotted-disk structure, a single demountable S-band cavity and a short X-band structure which has not yet been tested. The demountable cavity was built specifically to examine the effects of copper quality, surface conditioning, gaseous exposures, and surface damage. Results to date and recent theoretical conjectures are discussed.

Download or read book W band LiGA Fabricated Klystron written by Liqun Song and published by . This book was released on 2002 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2005 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Gradient Accelerating Structure Proceedings Of The Symposium On The Occasion Of 70th Birthday Of Junwen Wang written by Wei Gai and published by World Scientific. This book was released on 2014-10-24 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume, for the symposium in honor of Junwen Wang's 70th anniversary, is dedicated to his many important achievements in the field of accelerator physics.It includes the discussions of recent advances and challenging problems in the field of high gradient accelerating structure development.

Download or read book PROGRESS REPORT ON HIGH GRADIENT RF STUDIES IN COPPER ACCELERATOR STRUCTURES written by G.A. LOEW and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book X Band Photonic Band Gap Accelerator Structure Breakdown Experiment written by and published by . This book was released on 2012 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to understand the performance of photonic band-gap (PBG) structures under realistic high gradient, high power, high repetition rate operation, a PBG accelerator structure was designed and tested at X band (11.424 GHz). The structure consisted of a single test cell with matching cells before and after the structure. The design followed principles previously established in testing a series of conventional pillbox structures. The PBG structure was tested at an accelerating gradient of 65 MV/m yielding a breakdown rate of two breakdowns per hour at 60 Hz. An accelerating gradient above 110 MV/m was demonstrated at a higher breakdown rate. Significant pulsed heating occurred on the surface of the inner rods of the PBG structure, with a temperature rise of 85 K estimated when operating in 100 ns pulses at a gradient of 100 MV/m and a surface magnetic field of 890 kA/m. A temperature rise of up to 250 K was estimated for some shots. The iris surfaces, the location of peak electric field, surprisingly had no damage, but the inner rods, the location of the peak magnetic fields and a large temperature rise, had significant damage. Breakdown in accelerator structures is generally understood in terms of electric field effects. These PBG structure results highlight the unexpected role of magnetic fields in breakdown. The hypothesis is presented that the moderate level electric field on the inner rods, about 14 MV/m, is enhanced at small tips and projections caused by pulsed heating, leading to breakdown. Future PBG structures should be built to minimize pulsed surface heating and temperature rise.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1994 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reviews Of Accelerator Science And Technology Volume 9 Technology And Applications Of Advanced Accelerator Concepts written by Alexander Wu Chao and published by World Scientific. This book was released on 2017-02-20 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its invention in the 1920s, particle accelerators have made tremendous progress in accelerator science, technology and applications. However, the fundamental acceleration principle, namely, to apply an external radiofrequency (RF) electric field to accelerate charged particles, remains unchanged. As this method (either room temperature RF or superconducting RF) is approaching its intrinsic limitation in acceleration gradient (measured in MeV/m), it becomes apparent that new methods with much higher acceleration gradient (measured in GeV/m) must be found for future very high energy accelerators as well as future compact (table-top or room-size) accelerators. This volume introduces a number of advanced accelerator concepts (AAC) — their principles, technologies and potential applications. For the time being, none of them stands out as a definitive direction in which to go. But these novel ideas are in hot pursuit and look promising. Furthermore, some AAC requires a high power laser system. This has the implication of bringing two different communities — accelerator and laser — to join forces and work together. It will have profound impact on the future of our field.Also included are two special articles, one on 'Particle Accelerators in China' which gives a comprehensive overview of the rapidly growing accelerator community in China. The other features the person-of-the-issue who was well-known nuclear physicist Jerome Lewis Duggan, a pioneer and founder of a huge community of industrial and medical accelerators in the US.