RFQ Integrated Design• Would like to have a

method of designing RFQ where all steps are integrated:– Engineering design.– EM modelling.– Beam dynamics

simulations.• Integrating design steps

allows us to characterise effects of:– Fringe fields and higher

order modes.– Limitations of current

modelling techniques.– Thermal and mechanical

stress limits.– Particular CNC machining

techniques and options on beam dynamics.

24/02/11 Simon Jolly, Imperial College London

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RFQ Integrated Design Steps

24/02/11

RFQSIMInventor (CAD)

Comsol

GPT

Matlab

Integrate RFQSIM, Inventor, Comsol, GPT and Matlab

Excel

Matlab

2Simon Jolly, Imperial College London

CAD & E-field Modelling

• Electrostatic field mapping in Comsol almost complete:– Semi-automated modelling of individual

cells: almost fully automated, just working out the gremlins…

– Already produced high resolution field map from CAD model for beam dynamics simulations.

– Currently focusing on design of matching-in and -out sections.

• CAD modelling of vane tip modulations now complete:– Using values in Excel spreadsheet, possible to create arbitrary vane

modulation design up to 1,000 cells in less than a minute.– Vane tip modulation model already added to bulk FETS RFQ CAD model:

ready for machining.

24/02/11 Simon Jolly, Imperial College London

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Beam Dynamics Simulations

24/02/11 Simon Jolly, Imperial College London

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Energy Spread (60mA)

Transmission (60mA)

• Beam dynamics simulations carried out in GPT using field maps.

• For nominal 60mA beam, CAD-based field map gives very similar results to coefficient-based field map from RFQSIM (A. Letchford):– >92% transmission of particles above

2.9MeV.– Slight difference in energy spread and

transmission: CAD-based map gives better transmission at high currents!