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Mechanical design of a rf electron gun

Description: Brookhaven National Laboratory is building an Accelerator Test Facility at which we plan to study laser acceleration of electrons inverse free electron lasers and the production of X-rays by non- linear Compton scattering. The facility contains an electron gun, linac, lasers and ancillary systems which will enable the production of 6 ps duration pulses of 50--100 MeV electrons. The electron source is an one and one half cell RF Electron gun which utilizes either a thermionic or photoemissive cathode to produce 5 MeV electrons. This paper discusses how gun mechanical design considerations such as material, vacuum maintenance, surface finish, fabrication methods, cavity tuning, and cathode replacement were reconciled to arrive at the final design. 9 refs., 2 figs., 2 tabs.
Date: January 1, 1988
Creator: Woodle, M.H.; Batchelor, K. & Sheehan, J.
Partner: UNT Libraries Government Documents Department

The Fermilab Main Injector

Description: The Fermilab Main Injector is a new 150 GeV proton synchrotron, designed to replace the Main Ring and improve the high energy physics potential of Fermilab. The status of the Fermilab accelerator complex upgrade will be discussed.
Date: November 1, 1992
Creator: Mishra, C.S.
Partner: UNT Libraries Government Documents Department

Some estimation concerning crossing transition of the main injector

Description: We estimate some parameters pertaining to the transition crossing of the Main Injector. These include the nonadiabatic time, bunch length and bunch height at transition, the microwave growth across transition driven by a longitudinal impedance, and the parameters that govern the Umstaetter's and the Johnsen's effects. 9 refs., 1 tab.
Date: June 1, 1990
Creator: Ng, King-Yuen.
Partner: UNT Libraries Government Documents Department

Beam extraction from TeV accelerators using channeling in bent crystals

Description: Bent crystal channeling offers an interesting alternative for beam extraction from trans-GeV accelerators. Conventional extraction employs resonant beam blow-up coupled with electromagnetic beam deflecting channels. It is limited by the length of the available accelerator straight section. Channeling crystals require much less space. A five-step approach to applying crystal extraction in the Superconducting Super Collider (SSC) is discussed. Two steps, extraction from the 8 GeV Dubna Synchrophasotron and the 76 GeV Serpukhov accelerator, have occurred. The next possibility is extraction from a multi-hundred GeV superconducting accelerator. In the nineties the program could continue at UNK (3 TeV) and culminate at the TeV SSC. The possibilities and limitations of crystal extraction are reviewed. More information is needed on dechanneling in bent crystals including the effects of dislocations at TeV energies. Long, dislocation-free'' crystals are required. A more thorough understanding of the theory of crystal extraction is also desirable. 12 refs.
Date: August 1, 1989
Creator: Carrigan, R.A. Jr.; Toohig, T.E.; Tsyganov, E.N. (Fermi National Accelerator Lab., Batavia, IL (USA); Superconducting Super Collider Lab., Dallas, TX (USA) & Joint Inst. for Nuclear Research, Dubna (USSR))
Partner: UNT Libraries Government Documents Department

Experimental RFQ as injector to the CERN Linac I

Description: Since the successful development and testing of a radio-frequency quadrupole (RFQ) prototype at Los Alamos, the use of RFQs as injectors to the CERN linacs is being envisaged. As a pilot project, a 202.56-MHz RFQ for Linac I (Old Linac) is being built in close collaboration between Los Alamos and CERN. This project will be completed in about 15 months, a timescale imposed by other CERN programs. The CERN RFQ is based on the Los Alamos proven design approach, but will have to meet requirements of the existing CERN environment. The design characteristics of this accelerator are described, and some conclusions based on model work at CERN are given.
Date: January 1, 1981
Creator: Boltezar, E.; Haseroth, H. & Pirkl, W.
Partner: UNT Libraries Government Documents Department

Summary report: injection group

Description: The injector group attempted to define and address several problem areas related to the SSC injector as defined in the Reference Design Study (RDS). It also considered the topic of machine utilization, particularly the question of test beam requirements. Details of the work are given in individually contributed papers, but the general concerns and consensus of the group are presented within this note. The group recognized that the injector as outlined in the RDS was developed primarily for costing estimates. As such, it was not necessarily well optimized from the standpoint of insuring the required beam properties for the SSC. On the other hand, considering the extraordinary short time in which the RDS was prepared, it is an impressive document and a good basis from which to work. Because the documented SSC performance goals are ambitious, the group sought an injector solution which would more likely guarantee that SSC performance not be limited by its injectors. As will be seen, this leads to a somewhat different solution than that described in the RDS. Furthermore, it is the consensus of the group that the new, conservative approach represents only a modest cost increase of the overall project well worth the confidence gained and the risks avoided.
Date: January 1, 1984
Creator: Simpson, J.; Ankenbrandt, C.; Brown, B.; Hojvat, C.; Johnson, R.; Marriner, J. et al.
Partner: UNT Libraries Government Documents Department

Slow extraction at the SSC

Description: Resonant slow extraction at the SSC will permit fixed-target operation. Stochastic extraction appears to be a promising technique for achieving spill times of the order of 1000 s. However, systematic sextupole error fields in the SSC dipoles must be reduced a factor of twenty from the design values; otherwise the extraction process will be perturbed or suppressed. In addition, good regulation of the SSC power supplies is essential for smooth extraction over the spill period. 10 refs., 1 fig.
Date: January 1, 1985
Creator: Colton, E.P.
Partner: UNT Libraries Government Documents Department

Design of an electron beam spectral modification system

Description: We report the design of a spectral modification system (SMS) for use with the proposed NEAL linac-pulse stretcher ring, cw electron beam facility. The SMS allows tailoring of the energy distribution of electrons in beams produced by a pulsed linac operating in the transient beam loading (TBL) regime. Modification of the energy distribution of electrons injected into the pulse strecher ring will increase the duty factor of current extracted from the ring and improve the efficiency of the extraction process. Physically, the SMS consists of an anisochronous, achromatic magnetic lattice followed by a pair of traveling-wave accelerating sections. For beams in the energy range of 500 MeV to 4 GeV, TBL ripple on the energy envelope of microsecond long beam spills is expected to be reduced from 1% peak-peak to less than 0.01% while the desired width of the energy profile due to the phase extent of the microbunches in the beam spill is preserved.
Date: October 1, 1981
Creator: Sheppard, J.C.; York, R.C.; Norum, B.E. & McCarthy, J.S.
Partner: UNT Libraries Government Documents Department

Operating experience with the ALS linac

Description: The linac injector for the Advanced Light Source (ALS) at LBL was recently put into operation. Energy is 50 MeV, frequency 3 GHz. The electron gun delivers up to 6nC in a 3.0-ns bunch at 120 kV. A train of bunches is injected into a 1-Hz booster and accelerated to 1.5 GHz for storage ring injection. A magnetic analysis system is used for optimizing the linac. Measured beam properties from the gun and after acceleration in the linac are described. 9 refs., 3 figs.
Date: May 1, 1991
Creator: Selph, F. & Massoletti, D.
Partner: UNT Libraries Government Documents Department

Injection septum magnets for the Loma Linda medical accelerator

Description: The injection beamline runs over the last magnet before a long straight section and is then displaced downward 55.88 cm to the accelerator beamline. The displacement is magnetic and the final deflection onto the synchrotron orbit is by an electric kicker. The first component, the reverse septum magnet, bends the injection beam 25)degree) downward. This is followed by the injection septum (20)degree) bend upward) and the final injection kicker (5)degree) bend upward). The septum magnets produce a peak field of 3.4 K gauss at a current of 28,000 amperes within a 0.1 msec long pulse. The electric kicker produces a field of 7.3 KV/cm with a pulse length of 0.0011 msec. The septum magnets are similar to each other in construction with a bending radium of 72.7 cm. The curvature is required to increase the effective aperture. Each magnet has a single-turn copper coil bonded to a stainless steel plate for reinforcement. This eliminates insulating material, which could be subject to radiation damage, at the septum. The stainless steel plate is welded to the magnet laminations. The current is confined to the septum by the insulation between the laminations, which are a standard core material. The total septum thickness with shield is 1.227 cm. Pulsing the magnet eliminates the need for water cooling. 2 refs., 4 figs.
Date: September 22, 1987
Creator: Satti, J.A.
Partner: UNT Libraries Government Documents Department

Buncher system parameter optimization

Description: A least-squares algorithm is presented to calculate the RF amplitudes and cavity spacings for a series of buncher cavities each resonating at a frequency that is a multiple of a fundamental frequency of interest. The longitudinal phase-space distribution, obtained by particle tracing through the bunching system, is compared to a desired distribution function of energy and phase. The buncher cavity parameters are adjusted to minimize the difference between these two distributions. Examples are given for zero space charge. The manner in which the method can be extended to include space charge using the 3-D space-charge calculation procedure is indicated.
Date: January 1, 1981
Creator: Wadlinger, E.A.
Partner: UNT Libraries Government Documents Department

Numerical determination of injector design for high beam quality

Description: The performance of a free electron laser strongly depends on the electron beam quality or brightness. The electron beam is transported into the free electron laser after it has been accelerated to the desired energy. Typically the maximum beam brightness produced by an accelerator is constrained by the beam brightness deliverd by the accelerator injector. Thus it is important to design the accelerator injector to yield the required electron beam brightness. The DPC (Darwin Particle Code) computer code has been written to numerically model accelerator injectors. DPC solves for the transport of a beam from emission through acceleration up to the full energy of the injector. The relativistic force equation is solved to determine particle orbits. Field equations are solved for self consistent electric and magnetic fields in the Darwin approximation. DPC has been used to investigate the beam quality consequences of A-K gap, accelerating stress, electrode configuration and axial magnetic field profile.
Date: October 15, 1985
Creator: Boyd, J.K.
Partner: UNT Libraries Government Documents Department

Design of a pulsed switching magnet for the Bevalac

Description: The design and construction of a water cooled, pulsed, laminated core dipole magnet which has recently been installed at the Bevalac is described. This new, energy efficient magnet was funded by the DOE In-House Energy Management Program. The magnet has been specifically designed for maximum efficiency in power utilization and has replaced two dc powered magnets in the Bevalac switchyard. It will reduce energy usage by 747 MWh/yr, and it provides the capability of pulse-to-pulse switching in 0.7 seconds between two major beamline channels serving the nuclear science and radiotherapy programs at the /Bevalac. A unique feature of this magnet is the core design which utilizes an external structure that remains integral with the core laminations after assembly. The structure provides for both torsional and longitudinal rigidity of the core while also facilitating the precision assembly and compression of the core laminations without the use of special assembly fixtures. 2 refs., 4 figs., 1 tab.
Date: March 1, 1989
Creator: Abbott, S.; Alonso, J.; Brown, J.; Kalnins, J.; Krebs, G. & Reimers, R.
Partner: UNT Libraries Government Documents Department

Design of an integrally formed RFQ

Description: The design, construction and testing of a 410 MHz RFQ utilizing a new mechanical design concept has been completed at LBL. The RFQ is planned to be used at the Bevatron for injecting protons into the present heavy ion linac. The integral vane-cavity construction is a significant and unique feature of this RFQ design, wherein four walls with integral vanes are assembled to form the RFQ geometry. This design concept provides the capability of achieving precision vane alignment in minimal assembly time with no adjustments required. The design concept including material selection, plating, vacuum seal design, assembly and testing are described. 4 refs., 4 figs., 1 tab.
Date: March 1, 1989
Creator: Abbott, S.; Caylor, R.; Gough, R.; Howard, D.; MacGill, R. & Staples, J.
Partner: UNT Libraries Government Documents Department

Injection system design for the LBL (Lawrence Berkeley Laboratory) 1-2 GeV synchrotron radiation source

Description: The injection system for the LBL 1 to 2 GeV Synchrotron Radiation Source is designed to provide an electron beam of 400 mA at 1.5 GeV to the storage ring in a filling time of less than 5 minutes. An alternate mode of operation requires that 7.6 mA be delivered to one, or a few rf bunches in the storage ring. To accomplish these tasks, a high intensity electron gun, a 50 MeV electron linac, and a 1.5 GeV booster synchrotron are used. The performance requirements of the injector complex are summarized. The electron gun and subharmonic buncher, linac design, and linac to booster and booster to storage ring transport are discussed as well as the booster synchrotron. (LEW)
Date: March 1, 1987
Creator: Selph, F.; Jackson, A. & Zisman, M.S.
Partner: UNT Libraries Government Documents Department

Operation of the LBL ECR source injection system

Description: The injection system for the LBL 88-Inch Cyclotron ECR source has been in operation since October 1984. It consists of 7 meters of horizontal beam line following the ECR source analyzing magnet, and 4 meters of vertical beam line down the axis of the cyclotron. Beams throughout the cyclotron energy range of 1 to 32 MeV/u, and particles from protons to xenon have been injected and accelerated in the cyclotron on 1st, 3rd, 5th and 7th harmonic modes. A non-scaling mode of operation is used in which a source voltage of about 10 kV is used for all beams. The overall transmission from source analyzing magnet to cyclotron external beam is typically 10%. The reliability and stability of the system has been excellent.
Date: October 1, 1986
Creator: Clark, D.J. & Lyneis, C.M.
Partner: UNT Libraries Government Documents Department

Optimal magnet sorting procedure and application to the APS injector synchrotron

Description: A magnet sorting procedure for accelerators is developed. It is implemented in two steps. The first step is completely analytical in character while the second step involves the comparison of computed values with the measured error values. The method has been implemented for sorting the Advanced Photon source (APS) injector synchrotron dipoles and quadrupoles with excellent results.
Date: January 1, 1993
Creator: Koul, R.K.; Lopez, F. & Mills, F.E.
Partner: UNT Libraries Government Documents Department

Performance of the Fermilab Main Ring during the 1988-89 Tevatron collider operation

Description: The Fermilab Main Ring serves as injector for the Tevatron at 150 GeV/c and as a source of 120 GeV/c protons for antiproton production. This paper discusses the Main Ring performance/emdash/intensity, reliability, and efficiency/emdash/during the present Collider run. Also discussed are questions related to emittance and emittance growth, both transverse and longitudinal, and the impact of Main Ring losses on the Collider experiments. 4 refs., 3 figs.
Date: March 1, 1989
Creator: Martin, P.S.
Partner: UNT Libraries Government Documents Department

Electron-beam generation, transport, and transverse oscillation experiments using the REX injector

Description: The REX machine at LANL is being used as a prototype to generate a 4-MV, 4.5-kA, 55-ns flat-top electron beam as a source for injection into a linear induction accelerator of the 16-MeV Dual-Axis Radiographic Hydrotest facility. The pulsed-power sources drives a planar velvet cathode producing a beam that is accelerated through a foilless anode aperture and transported by an air core magnetic lens for injection into the first of 48 linear induction cells. Extensive measurements of the time-resolved (<1-ns) properties of the beam using a streak camera and high-speed electronic diagnostics have been made. These parameters include beam current, voltage, current density, emittance, and transverse beam motion. The effective cathode temperature is 117 eV, corresponding to a Lapostolle emittance of 0.96 mm-rad. Transverse oscillations of the transported beam have been observed via a differenced B-dot technique to be about {plus minus}100 {mu}m at 245 MHz. This beam motion has been correlated via detailed rf measurements of asymmetric transverse cavity modes in the A-K gap. 7 refs., 6 figs.
Date: January 1, 1991
Creator: Carlson, R.L.; Allison, P.W.; Kauppila, T.J.; Moir, D.C. & Ridlon, R.N.
Partner: UNT Libraries Government Documents Department

Fixed-target option for the SSC

Description: Three questions addressed are: (1) is slow extraction technically and economically feasible at the SSC; (2) can gas jet targets be used parasitically to produce secondary beams; (3) how can parasitic test beams be obtained during collider operation. 15 references. (GHT)
Date: January 1, 1984
Creator: Colton, E.
Partner: UNT Libraries Government Documents Department

Control and initial operation of the Fermilab BO low. beta. insertion

Description: The operation of the Fermilab BO low ..beta.. insertion involves the coordinated control of the 4 strings of quadrupoles of the insertion itself along with several magnetic correction elements (20 dipoles for the closed orbit, 2 quad circuits for betatron tunes, 1 skew quad circuit for coupling, and 2 sextupole circuits for chromaticity). When the beam is stored at high energy, these elements must correct the errors induced by the strong superconducting quadrupoles of the insertion as the optics are smoothly changed from the fixed target configuration to the low ..beta.. state. The techniques and control programs for these manipulations and initial tests using a single coasting beam are described. 6 refs., 4 figs.
Date: June 1, 1985
Creator: Finley, D.A.; Johnson, R.P. & Willeke, F.
Partner: UNT Libraries Government Documents Department

Generation and acceleration of high intensity beams in the SLC injector

Description: A new gun pulser and substantially increased focusing have been added to the first 100 m of the SLAC linac in order to provide a pair of intense electron bunches to the SLC damping ring. Each bunch from this injector must have 5 x 10/sup 10/ electrons, an invariant emittance ..gamma..epsilon less than or equal to 1.8 x 10/sup -3/ m-rad and the pair must have an energy spread of less than 2%. Wakefield instabilities present in earlier versions of this injector have been controlled by reducing the transverse beam dimension by a factor of 3.
Date: April 1, 1985
Creator: Ross, M.C.; Browne, M.J.; Clendenin, J.E.; Jobe, R.K.; Seeman, J.T.; Sheppard, J.C. et al.
Partner: UNT Libraries Government Documents Department