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Defect-related internal dissipation in mechanical resonators and the study of coupled mechanical systems.

Description: Understanding internal dissipation in resonant mechanical systems at the micro- and nanoscale is of great technological and fundamental interest. Resonant mechanical systems are central to many sensor technologies, and microscale resonators form the basis of a variety of scanning probe microscopies. Furthermore, coupled resonant mechanical systems are of great utility for the study of complex dynamics in systems ranging from biology to electronics to photonics. In this work, we report the detai… more
Date: January 1, 2007
Creator: Friedmann, Thomas Aquinas; Czaplewski, David A.; Sullivan, John Patrick; Modine, Normand Arthur; Wendt, Joel Robert; Aslam, Dean (Michigan State University, Lansing, MI) et al.
Partner: UNT Libraries Government Documents Department
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Cryogenic studies of rf accelerating structures, vintage 1978

Description: Cryogenically cooled rf cavity studies were undertaken at Los Alamos in 1978 to test the effectiveness of reduced temperature on the Q-enhancement of 450-MHz drift-tube linac structures. A complete facility was set up to do high power tests, not only at liquid nitrogen (LN/sub 2/) temperature but with liquid hydrogen (LH/sub 2/) as well. The cavity, Dewar, klystron test stand, and a remote outdoor enclosure were constructed. Hydrogen safety approval for the tests was obtained. Unfortunately, th… more
Date: January 1, 1986
Creator: Liska, D.; Uher, J. & Potter, J.
Partner: UNT Libraries Government Documents Department
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Superconducting multicell cavity development program at Los Alamos

Description: The superconducting rf (SCRF) cavity Development Program at Los Alamos has designed, fabricated, and tested single-cell niobium cavities at 3-GHz and 805-MHz. This work is being done in preparation for procuring and testing a multicell niobium cavity. The multicell cavity is designed to accelerate protons at [beta] = 0.9; initial tests will be without beam. Progammmatic changes have required us to modify our plans to install a 6800-liter helium cryostat and a 12.8-g/s helium pump. We will use a… more
Date: January 1, 1993
Creator: Rusnak, B.; Spalek, G.: Gray, E.; DiMarco, J.N.; DeHaven, R.; Novak, J.; Walstrom, P. et al.
Partner: UNT Libraries Government Documents Department
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Experimental Results in Superconducting Niobium Resonators for High-Brightness Ion Beam Acceleration

Description: Two niobium resonant cavities for high-brightness ion beam acceleration have been constructed and tested. The first was based on a coaxial quarter-wave geometry and was optimized for phase velocity {beta}{sub 0} = 0.15. This cavity, which resonates at 400 MHz in the fundamental mode, operated at an average (wall-to-wall) accelerating gradient of 12.9 MV/m under continuous-wave (cw) fields. At his gradient, a cavity Q of 1.4 {times} 10{sup 8} was measured. The second was based on a coaxial half-… more
Date: January 1, 1990
Creator: Delayen, J. R.; Bohn, C. L. & Roche, C. T.
Partner: UNT Libraries Government Documents Department
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Present status and probable future capabilities of heavy-ion linear accelerators

Description: The general characteristics of heavy-ion linacs are summarized, with emphasis on the similarities and differences of systems based on different technologies. The main design considerations of superconducting linacs are outlined, the many projects based on this technology are listed, and a new concept for a superconducting injector linac is described. The role of RFQ structures for heavy-ion acceleration is summarized. A concluding section lists some probable applications of heavy-ion accelerato… more
Date: April 30, 1984
Creator: Bollinger, L.M.
Partner: UNT Libraries Government Documents Department
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Phase and amplitude stabilization of beam-loaded superconducting resonators

Description: A model has been developed to analyze the static and dynamic behavior of superconducting accelerating cavities operated in self-excited loops in the presence of phase and amplitude feedback, ponderomotive effects, and beam loading. This is an extension of an earlier analysis of the stabilization of superconducting cavities which has been the basis of the control system of several superconducting accelerators but did not include beam loading. Conditions have been derived to ensure static and dyn… more
Date: January 1, 1992
Creator: Delayen, J. R.
Partner: UNT Libraries Government Documents Department
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Advanced electromagnetic design of cavities for high current accelerators

Description: For high-current accelerators such as those proposed for transmutation technologies or spallation sources, preconstruction numerical modeling has a high importance. Non axisymmetric cavities require a full 3-D modeling. A complex analysis of structures beyond tuning and the calculation of Q and shunt impedance is required and also the interaction with the mechanical properties of the structures has to be taken into account. This paper reports on recent work done at LANL for proposed beam funnel… more
Date: May 1, 1995
Creator: Krawczyk, F.L.
Partner: UNT Libraries Government Documents Department
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Pump down rate for SRF cavities

Description: This note is about calculations aimed at quantifying adequate pumping speeds of evacuation of normally humid clean-room air from typical Superconducting Radiofrequency (SRF) cavities. The subject is of high relevance to the semiconductor industry, where the yield of VLSI (Very Large Scale Integration) chip production is affected by micron size particles which may cause fatal defects to their micron and sub-micron features. The recent availability of particle counters capable of operating in vac… more
Date: February 1, 1992
Creator: Kuchnir, M. (Fermi National Accelerator Lab., Batavia, IL (United States)) & Knobloch, J. (Cornell Univ., Ithaca, NY (United States). Lab. of Nuclear Studies)
Partner: UNT Libraries Government Documents Department
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Status of the SUNY superconducting RFQ

Description: A RFQ resonator is presently being developed at SUNY. This resonator is a prototype for a chain of six short ({approximately}0.5m long), superconducting (Pb plated Cu), 50 MHz resonators designed to accelerate beam from {beta} = 0.01 to 0.05. The chain accepts a prebunched beam to save on superconducting length. The resonators are of four-rods type with vane-like electrodes. The prototype resonator is designed to accelerate ions of q/A = 1/6 from {beta} = 0.030 to 0.036, operating at a peak sur… more
Date: January 1, 1991
Creator: Jain, A.; Ben-Zvi, Ilan; Paul, P.; Wang, H. (Brookhaven National Lab., Upton, NY (United States)) & Lombardi, A. (Istituto Nazionale di Fisica Nucleare, Legnaro (Italy). Lab. Nazionale di Legnaro)
Partner: UNT Libraries Government Documents Department
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New fast tuning system for the Atlas Accelerator

Description: This paper will discuss field level limitations for on-line operation of the Argonne superconducting split-ring resonators. It also describes development of a new fast tuning system for the split-ring superconducting resonators. 1 ref., 1 fig.
Date: January 1, 1987
Creator: Zinkann, G.
Partner: UNT Libraries Government Documents Department
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High field rf superconductivity: to pulse or not to pulse

Description: Experimental data on the behavior of superconductors under the application of rf fields of amplitude comparable to their critical fields are sporadic and not always consistent. In many cases the field level at which breakdown in superconducting rf cavities should be expected has not been clearly established. Tests conducted with very short (approx. 1 ..mu..s) rf pulses indicate that in this mode of operation fields close to the critical values can be consistently reached in superconducting cavi… more
Date: October 1, 1984
Creator: Campisi, I.E.
Partner: UNT Libraries Government Documents Department
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New results on (LAMPF II) superconducting linac cost

Description: A consolidated cost estimate for a superconducting 800 MeV extension of the LAMPF I linac is presented in this note. Based on recent CERN-LEP tender results for 20 superconducting cavities, the cost of a superconducting linac structure (402.5 MHz) can be projected with much better accuracy than so far. The total construction cost for an 800 MeV extension amounts to 99.5 M$, buildings, cryoplant etc. included. The corresponding figure for a normal conducting structure (1207.5 MHz, on axis couple… more
Date: January 1, 1989
Creator: Schaffer, G.
Partner: UNT Libraries Government Documents Department
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Status of RF superconductivity at Argonne

Description: Development of a superconducting (SC) slow-wave structures began at Argonne National Laboratory (ANL) in 1971, and led to the first SC heavy-ion linac (ATLAS - the Argonne Tandem-Linac Accelerating System), which began regularly scheduled operation in 1978. To date, more than 40,000 hours of bean-on target operating time has been accumulated with ATLAS. The Physics Division at ANL has continued to develop SC RF technology for accelerating heavy-ions, with the result that the SC linac has, up to… more
Date: January 1, 1989
Creator: Shepard, K.W.
Partner: UNT Libraries Government Documents Department
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DAPHNE: a parallel multiprocessor data acquisition system for nuclear physics. [Data Acquisition by Parallel Histogramming and NEtworking]

Description: This paper describes a project to meet these data acquisition needs for a new accelerator, ATLAS, being built at Argonne National Laboratory. ATLAS is a heavy-ion linear superconducting accelerator providing beam energies up to 25 MeV/A with a relative spread in beam energy as good as .0001 and a time spread of less than 100 psec. Details about the hardware front end, command language, data structure, and the flow of event treatment are covered.
Date: January 1, 1984
Creator: Welch, L.C.
Partner: UNT Libraries Government Documents Department
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Superconducting cavities and modulated RF

Description: If a cavity has an infinite Q/sub o/, 81.5% of the energy contained in a pulse incident upon the cavity is transferred into the cavity by the end of the pulse if the cavity Q/sub e/ is chosen so that the cavity time constant is 0.796 pulse width (T/sub a/). As Q/sug o/ decreases, the energy in the cavity at the end of the pulse decreases very slowly as long as T/sub a/ is much less than the unloaded cavity time constant, T/sub co/. SC cavities with very high Q/sub o/ enable one to obtain very h… more
Date: February 1, 1981
Creator: Farkas, Z. D.
Partner: UNT Libraries Government Documents Department
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Calculation of mechanical vibration frequencies of stiffened superconducting cavities

Description: We calculated the frequencies of transverse and longitudinal mechanical-vibration modes of the HEPL- modified, CERN/DESY four-cell superconducting cavity, using finite-element techniques. We compared the results of these calculations, including the stiffening of the cavity with rods, with mode frequencies measured at HEPL. The correlation between data was significant. The same techniques were also used to design and optimize the stiffening scheme for the seven-cell 805-MHz superconducting cavit… more
Date: January 1, 1992
Creator: Black, S. J. & Spalek, G.
Partner: UNT Libraries Government Documents Department
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Review of superconducting ion linacs

Description: This paper summarizes the status of the technology of superconducting (SC) linacs designed for the acceleration of ions. The emphasis is on the technical issues involved, with only brief descriptions of the numerous linacs now in operation or under construction. Recent developments of special interest are treated in more detail, and remaining technical challenges are outlined. The technology required for the acceleration of ions with velocity [beta]=1 is not discussed because it is almost the s… more
Date: January 1, 1992
Creator: Bollinger, L. M.
Partner: UNT Libraries Government Documents Department
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Model measurements for new accelerating techniques

Description: We summarize the work carried out for the past two years, concerning some different ways for achieving high-field gradients, particularly in view of future linear lepton colliders. These studies and measurements on low power models concern the switched power principle and multifrequency excitation of resonant cavities. 15 refs., 12 figs.
Date: June 1, 1988
Creator: Aronson, S.; Haseroth, H.; Knott, J. & Willis, W.
Partner: UNT Libraries Government Documents Department
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MTA Mark II Accelerator, Drift Tube and RF Beam Geometry Perturbing Effect of Beam in A-12

Description: The question has arisen of how the beam in A-12 as a long resonant cavity might effect the frequency of operation and the field distribution. This study is published to make available the calculation of the direct beam effect as an illustration of general methods of attacking perturbing effects in resonant cavities.
Date: April 8, 1952
Creator: Good, Myron
Partner: UNT Libraries Government Documents Department
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Preliminary Investigation of Helmholtz Resonators for Damping Pressure Fluctuations in 3.6-Inch Ram Jet at Mach Number 1.90

Description: Memorandum presenting an investigation conducted at Mach number 1.90 to determine if Helmholtz resonators can be used in a typical ramjet configuration to damp pressure pulsations associated with shock oscillations. Only one of the two resonators was found to effectively damp pressure pulsations that occurred when the ram jet was operating in the vicinity of its peak pressure recovery. Neither was found to effectively damp pressure pulsations over the entire range of ramjet operating conditions. more
Date: May 22, 1951
Creator: Fox, Jerome L.
Partner: UNT Libraries Government Documents Department
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