Author: van der Geer, S.B.
Paper Title Page
WEPC085 Multipole Fringe Fields 2211
 
  • B.D. Muratori, J.K. Jones
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • M.J. de Loos, S.B. van der Geer
    Pulsar Physics, Eindhoven, The Netherlands
 
  When cre­at­ing an ini­tial model of an ac­cel­er­a­tor, one usu­al­ly has to re­sort to a hard edge model for the quadrupoles and high­er order mul­ti­poles at the start of the pro­ject. Or­di­nar­i­ly, it is not until much later on that one has a field map for the given mul­ti­poles. This can be rather in­con­ve­nient when one is deal­ing with par­tic­u­lar­ly thin el­e­ments or el­e­ments which are rather close to­geth­er in a beam­line as the hard edge model may be in­ad­e­quate for the level of pre­ci­sion de­sired. For ex­am­ple, in the EMMA pro­ject, the two types of quadrupoles used are so close to­geth­er that they are usu­al­ly de­scribed by a sin­gle field map or via hard edge mod­els. The first method has the de­sired ac­cu­ra­cy but was not avail­able at the start of the pro­ject and the sec­ond is known to be a rough ap­prox­i­ma­tion. In this paper, an an­a­lyt­ic ex­pres­sion is de­rived and pre­sent­ed for fringe fields for a mul­ti­pole of any order with a view to ap­ply­ing it to cases like EMMA.  
 
WEPC102 Recent Developments for Efficient 3D Space Charge Computations Based on Adaptive Multigrid Discretizations 2253
 
  • G. Pöplau, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • M.J. de Loos
    TUE, Eindhoven, The Netherlands
  • S.B. van der Geer
    Pulsar Physics, Eindhoven, The Netherlands
 
  Funding: Partly supported by BMBF under contract number 05K10HRC
Ef­fi­cient and ac­cu­rate space-charge com­pu­ta­tions are es­sen­tial for the de­sign of high-bright­ness charged par­ti­cle sources. Re­cent­ly a new adap­tive mesh­ing strat­e­gy based on multi­grid was im­ple­ment­ed in GPT and the ca­pa­bil­i­ties were demon­strat­ed. This new mesh­ing scheme uses the so­lu­tion of an in­ter­me­di­ate step in the multi­grid al­go­rithm it­self to de­fine op­ti­mal mesh line po­si­tions. In this paper we dis­cuss fur­ther de­vel­op­ments of this adap­tive mesh­ing strat­e­gy. We com­pare the new al­go­rithm with the cur­rent mesh­ing scheme of GPT, where the mesh line po­si­tions are based upon the pro­ject­ed charge den­si­ty.