1 PIC versus Frozen? 5/27/2013 FSOutcome of SC-13 PIC codes are definitely needed when coherent...

1 PIC versus Frozen? 5/27/2013 FS Outcome of SC-13 • PIC codes are definitely needed when coherent effects are relevant. • In our case in presence of strong space charge, time varying fields, double RF at the beginning of injection using PTC-ORBIT makes a lot of sense! • However, one of the main SC-13 outcomes is the fact that probably the most relevant issues are of incoherent nature Frozen space charge approach ➔ might be sufficient for many aspects of our studies. • Frozen space charge codes are 10-100 faster Long ➔ time scales • Clearly for the simulations of 1.2s of the PS only frozen space charge codes can do the job! • It has been argued that the half integer resonance in the PSB is a good candidate for coherent phenomena. However, a half integer resonance compensation improves losses a lot needs studies. ➔ • MAD-X in the newest version has the frozen space charge implemented and by the way with time varying

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Transcript of 1 PIC versus Frozen? 5/27/2013 FSOutcome of SC-13 PIC codes are definitely needed when coherent...

PIC versus Frozen?

5/27/2013 FS Outcome of SC-13

• PIC codes are definitely needed when coherent effects are relevant.

• In our case in presence of strong space charge, time varying fields, double RF at the beginning of injection using PTC-ORBIT makes a lot of sense!

• However, one of the main SC-13 outcomes is the fact that probably the most relevant issues are of incoherent nature Frozen space ➔charge approach might be sufficient for many aspects of our studies.

• Frozen space charge codes are 10-100 faster Long time scales➔• Clearly for the simulations of 1.2s of the PS only frozen space

charge codes can do the job! • It has been argued that the half integer resonance in the PSB is a

good candidate for coherent phenomena. However, a half integer resonance compensation improves losses a lot needs studies.➔

• MAD-X in the newest version has the frozen space charge implemented and by the way with time varying fields.

• Example for the Fermilab Debuncher shows quite similar results.

Page 2: 1 PIC versus Frozen? 5/27/2013 FSOutcome of SC-13 PIC codes are definitely needed when coherent effects are relevant. In our case in presence of strong.

Slow extraction in Debuncher using Orbit• 3-order resonance with variable tune Qx and sext. str. K2• First “strange” results for extraction: “intensity drop”

intensity vs turns

• “Intensity drop” was resolved simply at the beginning: Valery advised to make mesh refinements

PIC: “Total Beam size increases at slow extraction => mesh number should be increased to keep the cell size”