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Design of high power injection heaters for the ORMAK system

Description: From fifth symposium on engineering problems of fusion research; Princeton, New Jersey, USA (6 Nov 1973). The development of neutral injectors at ORNL has stressed input power levels sufficient to heat plasma ions. It has also stressed other problems equally important for success in neutral-injection heating. Injection pulse lengths, which have been extended to 200 msec, will need to be extended further for tokamaks of the future. This requires the ORNL approach of energyefficiency, cooled ion sources, and dc supplies. Low bcam impurity content requires high duty--cycle cleanup, which again means energy efficiency, cooled sources, and dc supplies. Design of the injectors to have gas efficiency and to have sufficient auxiliary pumping is necessary to keep cold gas streaming down to levels not expected to perturb the tokamak plasma. (auth)
Date: January 1, 1973
Creator: Stewart, L.D.; Davis, R.C.; Ezell, J.C.; Jernigan, T.C.; Morgan, O.B.; Stirling, W.L. et al.
Partner: UNT Libraries Government Documents Department

Analysis of the January 2006 Pepper-Pot Experiments

Description: Between January 9-12, 2006 a series of experiments were performed on the DARHT-II injector to measure the beam's emittance. Part of these experiments were pepper-pot measurements. This note describes the analysis of the data, and our conclusions from the experiments.
Date: March 22, 2006
Creator: Westenskow, G; Chambers, F; Bieniosek, F & Henestroza, E
Partner: UNT Libraries Government Documents Department


Description: Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory have formed a consortium to provide components for the Large Hadron Collider (LHC) to be built at CERN. The U.S. contribution includes half of the high gradient quadrupoles (HGQ) for the inner focusing triplets. In this paper a description of the HGQ magnetic design is given, including short sample limit for field gradient, sources and expected values of systematic and random field errors, and possible strategies for field quality correction.
Date: May 12, 1997
Creator: Sabbi, G.; Gourlay, S. A.; Kerby, J.; Lamm, M. J.; Limon, P. J.; Nobrega, F. et al.
Partner: UNT Libraries Government Documents Department

Coupled spheromak-helicity injector in the sustained spheromak physics experiment, SSPX

Description: The Sustained Spheromak Physics Experiment, now under construction at LLNL, will be sustained by helicity injected from a coaxial plasma source. The ideal MHD equilibrium of the coupled spheromak and source plasmas is calculated in this report, with the plasma in the injector treated in the force free approximation. The two regions are linked by a current-carrying edge plasma region, with field lines which end on the injector electrodes and a width determined by the ratio of the poloidal flux applied to the injector by external coils and that generated in the spheromak. The safety factor, q, on the magnetic axis and its profile within the spheromak separatrix are determined primarily by the ratio of the external and internal values of {lambda} =j{sub {vert_bar}{vert_bar}}/B and by the internal profile of {lambda}. The q-profile is expected to have significant effect on the operation of the experiment, particularly on the stability of the equilibrium and the associated magnetic dynamo.
Date: April 1, 1998
Creator: Hooper, E.B.
Partner: UNT Libraries Government Documents Department

Main Injector synchronous timing system

Description: The Synchronous Timing System is designed to provide sub-nanosecond timing to instrumen-tation during the acceleration of particles in the Main Injector. Increased energy of the beam particles leads to a small but significant increase in speed, reducing the time it takes to com-plete a full turn of the ring by 61 nanoseconds (or more than 3 RF buckets). In contrast, the reference signal, used to trigger instrumentation and transmitted over a cable, has a constant group delay. This difference leads to a phase slip during the ramp and prevents instrumentation such as dampers from properly operating without additional measures. The Synchronous Tim-ing System corrects for this phase slip as well as signal propagation time changes due to tem-perature variations. A module at the LLRF system uses a 1.2 Gbit/s G-Link chip to transmit the RF clock and digital data (e.g. the current frequency) over a single mode fiber around the ring. Fiber optic couplers at service buildings split off part of this signal for a local module which reconstructs a synchronous beam reference signal. This paper describes the background, design, and expected performance of the Synchronous Timing System.
Date: March 2, 1999
Creator: Steimel, Willem Blokland and James
Partner: UNT Libraries Government Documents Department

Chromaticity control in the Fermilab Main Injector

Description: Chromaticity control in the Fermilab Main Injector will be important both in accelerating protons and antiprotons from 8 GeV to 150 GeV (or 120 GeV) and in decelerating recycled 150 GeV antiprotons to 8 GeV for storage in the Recycler Ring. The Main Injector has two families of sextupoles to control the chromaticity. In addition to the natural chromaticity, they must correct for sextupole fields from ramp-rate-dependent eddy currents in the dipole beampipes and current-dependent sextupole fields in the dipole magnets. The horizontal sextupole family is required to operate in a bipolar mode below the transition energy of 20 GeV. We describe methods used to control chromaticities in the Fermilab Main Injector. Emphasis is given to the software implementation of the operator interface to the front-end ramp controllers. Results of chromaticity measurements and their comparison with the design model will be presented.
Date: April 16, 1999
Creator: al., G. Wu et
Partner: UNT Libraries Government Documents Department

A regulated magnetron pulser

Description: This paper describes and analysis of a 4.5-kV, 500-mA, regulated current pulser used to drive a Hitachi ZM130 magnetron in a particle-accelerator injector. In this application, precise beam from the injector. A high-voltage triode vacuum tube with active feedback is used to control the magnetron current. Current regulation and accuracy is better than 1%. The pulse width may be varied from as little as 5 {mu}m to cw by varying the width of a gate pulse. The current level can be programmed between 10 and 500 mA. Design of the pulser including circuit simulations, power calculations, and high-voltage issues are discussed.
Date: September 1, 1997
Creator: Rose, C.R.
Partner: UNT Libraries Government Documents Department

Design for Fermilab main injector magnet ramps which account for hysteresis

Description: Although the dominant fields in accelerator electromagnets are proportional to the excitation current, precise control of accelerator parameters requires a detailed understanding of the fields in Main Injector magnets including contribution from eddy currents, magnet saturation, and hysteresis. Operation for decelerating beam makes such considerations particularly significant. Analysis of magnet measurements and design of control system software is presented. Field saturation and its effects on low field hysteresis are accounted for in specifying the field ramps for dipole, quadrupole and sextupole magnets. Some simplifying assumptions are made which are accepted as limitations on the required ramp sequences. Specifications are provided for relating desired field ramps to required current ramps for the momentum, tune, and chromaticity control.
Date: May 1, 1997
Creator: Brown, B.C.; Bhat, C.M.; Harding, D.J.; Martin, P.S. & Wu, G.
Partner: UNT Libraries Government Documents Department

Development of a 110-m-mA, 75-keV proton injector for high-current, CW linacs

Description: A dc proton injector is being developed for a 6.7 MeV CW RFQ at Los Alamos. The RFQ input beam requirements are 75 keV energy, 110 mA dc proton current, and 0.20 {pi}mm-mrad rms normalized emittance. The injector has now produced a 75-keV, 117-mA dc proton beam (130 mA total current) with the required emittance. The emittance has been measured after a 2.1 m long two-solenoid beam transport system. The measured emittance can be explained in terms of the ion source emittance and beam transport through the focusing elements. Measured proton fractions are 90-92% of the beam current. Engineering of the accelerating column high-voltage design is being improved to increase the injector reliability. Injector design details and status are presented.
Date: September 1, 1996
Creator: Sherman, J.D.; Bolme, G.O. & Hansborough, L.D.
Partner: UNT Libraries Government Documents Department

The coupling impedance of the RHIC injection kicker system

Description: In this paper, results from impedance measurements on the RHIC injection kickers are reported. The kicker is configured as a {open_quotes}C{close_quotes} cross section magnet with interleaved ferrite and high-permittivity dielectric sections to achieve a travelling wave structure. The impedance was measured using the wire method in which a resistive match provides a smooth transition from the network analyzer to the reference line in the set-up. Accurate results are obtained by interpreting the forward scattering coefficient via the log-formula. The four kickers with their ceramic beam tubes contribute a Z/n = 0.22 {Omega}/ring in the interesting frequency range from 0.1 to 1 GHz, and less above. At frequencies above {approximately}100 MHZ, the impedance is ferrite dominated and not affected by the kicker terminations. Below 100 MHz, the Blumlein pulser with the {approximately}75 m feeding cables is visible in the impedance but makes no significant contribution to the results. The measurements show that the kicker coupling impedance is tolerable without the need for impedance reducing measures.
Date: July 1, 1997
Creator: Hahn, H. & Ratti, A.
Partner: UNT Libraries Government Documents Department

Slow extraction from the Fermilab Main Injector

Description: Slow resonant extraction from the Fermilab Main Injector through the extraction channel was achieved in February, 2000, with a spill length of 0.3 sec. Beam losses were small. Excellent wire chamber profiles were obtained and analyzed. The duty factor was not very good and needs to be improved.
Date: July 20, 2001
Creator: al., Craig D. Moore et
Partner: UNT Libraries Government Documents Department

Field errors introduced by eddy currents in Fermilab main injector magnets

Description: The Fermilab Main Injector ramps from 8 GeV to 120 GeV in about half a second. The rapidly changing magnetic field induces eddy currents in the stainless steel vacuum tubes, which in turn produce error fields that can affect the beam. Field calculations and measurements are presented for the dipole and quadrupole magnets.
Date: October 1, 1997
Creator: Walbridge, D.G.C.; Brown, B.C.; Dinanco, J.B.; Sharoran, S.A. & Sim, J.W.
Partner: UNT Libraries Government Documents Department

Switchyard in the Main Injector era conceptual design report

Description: This report presents elements of a design of the Switchyard and of the present fixed target beamlines in the era of the Main Injector (MI). It presumes that 800 GeV Tevatron beam will be transported to this area in the MI era, and permits it to share cycles with 120 GeV Main Injector beam if this option is desired. Geographically, the region discussed extends from the vicinity of AO to downstream points beyond which beam properties will be determined by the requirements of specific experiments. New neutrino lines not utilizing the present Switchyard (NuMI, BooNE) are not addressed. Similarly Main Injector beams upstream of AO are described fully in MI documentation and are unaffected by what is presented here. The timing both of the preparation of this report and of its recommendations for proceeding with construction relate to a desire to do required work in Transfer Hall and Enclosure B during the Main Injector construction shutdown (September 1997 - September 1998). As these areas are off-limits during any Tevatron operation, it is necessary for the fixed target program that work be completed here during this extended down period. The design presented here enables the operation of all beamlines in the manner specified in the current Laboratory plans for future fixed- target physics.
Date: August 1, 1997
Creator: Brown, C.; Kobilarcik, T.; Lucas, P.; Malensek, A.; Murphy, C.T. & Yang, M.-J.
Partner: UNT Libraries Government Documents Department

Intensity Limitations in Fermilab Main Injector

Description: The design beam intensity of the FNAL Main Injector (MI) is 3 x 10{sup 13} ppp. This paper investigates possible limitations in the intensity upgrade. These include the space charge, transition crossing, microwave instability, coupled bunch instability, resistive wall, beam loading (static and transient), rf power, aperture (physical and dynamic), coalescing, particle losses and radiation shielding, etc. It seems that to increase the intensity by a factor of two from the design value is straightforward. Even a factor of five is possible provided that the following measures are to be taken: an rf power upgrade, a {gamma}{sub t}-jump system, longitudinal and transverse feedback systems, rf feedback and feedforward, stopband corrections and local shieldings.
Date: June 1, 1997
Creator: Chan, W.
Partner: UNT Libraries Government Documents Department

Generation of angular-momentum-dominated electron beams from a photoinjector

Description: Various projects under study require an angular-momentum-dominated electron beam generated by a photoinjector. Some of the proposals directly use the angular-momentum-dominated beams (e.g. electron cooling of heavy ions), while others require the beam to be transformed into a flat beam (e.g. possible electron injectors for light sources and linear colliders). In this paper, we report our experimental study of an angular-momentum-dominated beam produced in a photoinjector, addressing the dependencies of angular momentum on initial conditions. We also briefly discuss the removal of angular momentum. The results of the experiment, carried out at the Fermilab/NICADD Photoinjector Laboratory, are found to be in good agreement with theoretical and numerical models.
Date: November 30, 2004
Creator: Sun, Yin-E.; Piot, Philippe; Kim, Kwang-Je; Barov, Nikolas; Lidia, Steven; Santucci, James et al.
Partner: UNT Libraries Government Documents Department

A positron accumulator ring for APS

Description: The new positron injection scheme is as follows. The cycle rate of the injector synchrotron is increased to 2 Hz. During 0.4 sec of each 0.5-sec synchrotron cycle, 24 linac pulses are injected into the horizontal phase space of the PAR at a 60-Hz rate. Each injected pulse occupies about 1/3 of the circumference of the accumulator ring. After 0.1 sec for longitudinal damping, the single accumulated bunch is transferred into one of the 352.96-MHz buckets of the injector synchrotron RF system. This single bunch is accelerated to 7 GeV and transferred into the storage ring while the PAR accumulates the next bunch of positrons. The injector synchrotron requires only the one high-frequency RF system.
Date: March 1, 1988
Creator: Crosbie, E.A.
Partner: UNT Libraries Government Documents Department