Estimation of Transverse Thermal Conductivity of Doubly-periodic Fiber Reinforced Composites

For steady-state heat conduction a new variational functional for a unit cell of composites with periodic microstructures is constructed by considering the quasi-periodicity of the temperature field and in the periodicity of the heat flux fields. Then by combining with the eigenfunction expansion of complex potential which satisfies the fiber-matrix interface conditions, an eigenfunction expansion-variational method (EEVM) based on a unit cell is developed. The effective transverse thermal conductivities of doubly-periodic fiber reinforced composites are calculated, and the first-order approximation formula for the square and hexagonal arrays is presented,which is convenient for engineering application. The numerical results show a good convergency of the presented method, even through the fiber volume fraction is relatively high. Comparisons with the existing analytical and experimental results are made to demonstrate the accuracy and validity of the first-order approximation formula for the hexagonal array.

Commissioning of electron cooling in CSRm

A new generation electron cooler has started operation in the heavy ion synchrotron CSRm which is used to increase the intensity of heavy ions. Transverse cooling of the ion beam after horizontal multi-turn injection allows beam accumulation at the injection energy. After optimization of the accumulation process an intensity increase in a synchrotron pulse by more than one order of magnitude has been achieved. In given accumulation time interval of 10 seconds, 108particles have been accumulated and accelerated to the final energy. The momentum spread after accumulation and acceleration in the 10−4 range has been demonstrated in six species of ion beams. Primary measurements of accumulation process varying with electron energy,electron beam current, electron beam profile, expansion factor and injection interval have been performed.The lifetimes of ion beams in the presence of electron beams were roughly measured with the help of DCCT signal.

A new dual injection system for AMS facility

IEECAS SKLLQG

Collective Transverse Flow in Intermediate Energy Heavy-Ion Collisions

Within the hadronic transport model IBUU04, we study the density-dependent symmetry energy by using the neutron-proton differential flow from the Sn-132+Sn-124 reactions at beam energies of 200, 400, 600 and 800MeV per nucleon. The strong effect of the symmetry energy is shown at the incident beam energy of 400 MeV/A. The small medium-effect of the neutron-proton differential flow is also found. We also study the neutron-proton differential flows with impact parameters of 3, 5, 7 fm. It is found that in semi-central collisions the sensitivity of the neutron-proton differential flow to the symmetry energy is larger.

Low conductance injection tubes for storage cell targets

The effect of adding internal fins to the injection tube of a storage cell target filled with a polarized atomic beam source has been studied. The tube conductance and the atomic beam intensity at the exit of the injection tube have been measured, observing an unexpectedly large beam loss. Simulations of the atomic beam reproduce the observed attenuation only when the non-zero azimuthal component of the atom's velocity is taken into account.

Beam dynamics design of an RFQ for a planned accelerator, which uses a direct plasma injection scheme

To meet the requirements of providing high-intensity heavy ion beams the direct plasma injection scheme (DPIS) was proposed by a RIKEN-CNS-TIT collaboration. In this scheme a radio frequency quadrupole (RFQ) was joined directly with the laser ion source (LIS) without a low-energy beam transport (LEBT) line. To find the best design of the RFQ that will have short length, high transmission efficiency and small emittance growth, beam dynamics designs with equipartitioning design strategy and with matched-only design strategy have been performed, and a comparison of their results has also been done. Impacts of the input beam parameters on transmission efficiency are presented, too. (C) 2008 Elsevier B.V. All rights reserved.

Injection system design for a hadron therapy synchrotron

A synchrotron is designed for tumour therapy with C6+ ions or proton. Its injector is a cyclotron, which delivers C5+ or H-2(+) ions to the synchrotron. After comparing the methods of the single-turn injection, the multi-turn injection and the stripping injection, this paper chooses the stripping injection method. In addition, the concept design of the injection system is presented, in which the synchrotron lattice is optimized.

A transverse field gas ionization chamber performed at RIBLL

A transverse field gas ionization chamber as Delta E detector at the Radioactive Ion Beam Line in Lanzhou (RIBLL) is described. A high detection efficiency and long plateau are achieved with the mixed gas Ar(80%)+CO2(20%). The energy resolution is 3.25% for 4.94MeV alpha particle. This ionization chamber has been tested in the experiment with 50MeV/u Ni-58 bombarding Ta at RIBLL. All the fragments can be identified clearly by the ionization chamber.

Double neutron-proton differential transverse flow as a probe for the high density behavior of the nuclear symmetry energy

The double neutron-proton differential transverse flow taken from two reaction systems using different isotopes of the same element is studied at incident beam energies of 400 and 800 MeV/nucleon within the framework of an isospin- and momentum-dependent hadronic transport model IBUU04. The double differential flow is found to retain about the same sensitivity to the density dependence of the nuclear symmetry energy as the single differential flow in the more neutron-rich reaction. Because the double differential flow reduces significantly both the systematic errors and the influence of the Coulomb force, it is thus more effective probe for the high-density behavior of the nuclear symmetry energy.

Study of buncher efficiency in axial injection system of SFC

In order to reduce the influence of the stray electric field of the buncher in the axial injection system of SFC and to improve the injection efficiency of SFC, the existing buncher electrode is investigated and a new electrode is designed. The influences of the electric field to the beams for the both cases are simulated. The simulation results show that the bunching efficiency is improved from 55% to 74% with the new electrode. At the same time, the influence of the space charge is computed and according to the results, the location of the buncher is readjusted too.