Length Of Straight Section Research Articles

Beam extraction from TeV accelerators using channeling in bent crystals

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 20 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.

Potential core of an axisymmetric laminar jet. 2nd Report. The effect of a nozzle.

In the preceding paper, the flow pattern in the flow developing region of an axisymmetric laminar water jet has been made clear. The experiments, however, were carried out by using a single nozzle, so that the potential core radius at the nozzle exit was determined only by the jet Reynolds number. In this paper, four nozzles with which the length of straight pipe section differed from each other were used, in order to clarify the effect of the initial jet profile at the nozzle exit on the flow in the flow developing region. The numerical examples obtained from the preceding method were also given. The effects of the supply nozzles on the velocity profile, the centerline velocity, the half-radius and the potential core radius were discussed.

Conceptual design of a 1.1-GeV 500-μa fast cycling proton synchrotron

A very high intensity proton synchrotron system which could be used for a pulsed spallation neutron source and low energy neutrino and meson physics facility is designed. The synchrotron would accelerate 200 MeV protons to 1.1 GeV with a repetition rate of 50 pulses per sec. The number of protons per pulse is 6.3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> , resulting in an average proton current of 500 μA. In order to accomodate the high intensity considerable attention was directed toward minimizing beam loss, controlling space charge forces, and eliminating beam instabilities. Special features of the conceptual design include H <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> charge exchange injection, a guide field flat-bottom of 1.5 msec to facilitate low-loss injection and capture, 15 msec acceleration period, and 3.5 msec for reset of the guide field. A separated function lattice consists of normal cells, dispersion suppressor cells, and matching cells. It provides sufficient straight section length to accommodate a fairly long rf system. A low impedance rf system (cathode-follower) is considered in order to overcome strong beam loading effects in the cavities. Rapid bunch shaping is employed at the end of acceleration to produce pulses of 200 nsec duration for possible neutrino experiments. The transverse acceptances used in the design are: ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</sub> = 500 π mm mr and ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</sub> = 300 π mm mr.

Soil-Pipe Interaction of Heated Oil Pipelines

A study is presented analyzing the distress frequently encountered in buried heated oil pipelines due to the expansion and contraction producing soil-pipe interface shear and cyclic movements. This movement can damage the coating of the pipe and result in corrosion failure. The magnitude of the cyclic shear stress and movement depends on temperatures, soil properties, and pipeline design items such as the length of casing, bend, and straight pipe sections. Two important factors are the coefficient of horizontal subgrade reaction and the soil-pipe interface shear parameter. The interface shear parameter is unique to the heated pipeline problem and can serve as a coating performance and selection criteria. Methods to calculate pipe movements and ways to restrain such movements are analyzed. Actual field measurements of a heated oil pipeline are compared with theoretical calculations.

The Dynamics of a Synchrotron with Straight Sections

The equations describing the ``betatron'' and ``synchrotron'' oscillations of a particle being accelerated in a synchrotron having straight sections are obtained. In particular, the relative increase in the ratio of either betatron-oscillation frequency to the frequency of revolution is found to be approximately half the ratio of the total length of straight sections to the orbit circumference. The effect of magnetic fringing fields is considered. With regard to the synchrotron phase oscillation, it is found that the criterion of non-relativistic adiabatic damping is no longer that n exceed ⅔ but that it exceed ⅔ by at least ⅓ of the ratio of the total length of the straight sections to the orbit circumference.