Longitudinal Stability of Flat Bunches with Space-Charge or Inductive Impedance
We study the loss of Landau damping for the longitudinal plane via the “Sacherer formalism”. Stability limits are calculated for several longitudinal beam distributions, in particular for two types of flat bunches, which could be of interest to the LHC upgrade. The resulting stability diagrams are computed and displayed for different azimuthal modes. A general recipe is given for calculating the threshold intensity in the case of a capacitive impedance below transition or, equivalently, for a purely inductive impedance above transition. The formalism was applied to the case of the PS Booster, as an example of space-charge impedance below transition, and to the SPS, as an example of inductive impedance above transition. Contribution to the EPAC’08 Conference, Genoa (Italy), 23-27 June 2008 Work supported by the European Community-Research Infrastructure Activity under the FP6 “Structuring the European Research Area” programme (CARE, contract number RII3-CT2003-506395) Longitudinal Stability of Flat Bunches with Space-Charge or Inductive Impedance I. Santiago Gonzalez ∗, F. Zimmermann, CERN, Geneva, Switzerland
Bucket Shaking Stops Bunch Oscillations In The Tevatron
Bunches in the Tevatron are known to exhibit longitudinal oscillations which persist indefinitely. These oscillations are colloquially called "dancing bunches". Although the dancing bunches do not cause single bunch emittance growth or beam loss at injection, it leads to bunch lengthening at collisions. In operations, a longitudinal damper has been built which stops this dance and damps out coupled bunch modes. Recent theoretical work predicts that the dance can also be stopped by an appropriate change in the bunch distribution. This paper shows the Tevatron experiments which support this theory.
Generalized energy efficiency of a nuclear power station derived from the reactor fuel reproduction ratio and the overall efficiency
The authors construct algorithms for calculating and optimizing the overall energy efficiency of nuclear power plants which are based on hydraulic and heat transfer considerations and reactor lattice parameters as well as fuel management and cycle and reactor fueling options including spent fuels reprocessing. They generalize their algorithms to a number of reactor efficiency scenarios including thermal neutron, LMFBR, fast, and WWER type reactors. The algorithms, for the case of breeder reactors, also incorporate breeding ratio parameters.