CEA Codes forum

Posted: **Wed 20 Oct 2021 13:35**

Dear Didier,
I've observed a transverse emittance growth at the end of any rfq, also with RFQ_1.ini, in the last very short drift.

: Emittance_growth.png (19.4 KiB) Viewed 1754 times

: rfq_end_drift.PNG (47.96 KiB) Viewed 1754 times

A so short drift cannot induce a so large emittance increase.
May you know why ?
Best Regards,
Michele Comunian

Posted: **Wed 20 Oct 2021 14:07**

Dear Didier,
reading the post,
I've removed from the emittance calculation the not accelerated particles.
The problem of transverse emittance growth is mitigate, but still present.
As you can see from the figures.

: Emittance_growth_with_longitudinal_cut.png (21.66 KiB) Viewed 1747 times

: Emittance_cut.PNG (7.8 KiB) Viewed 1747 times

Best Regards,
Michele Comunian

Posted: **Wed 20 Oct 2021 16:00**

Dear Michele,

Actually, the growth you see is due to the Fringe field section including gap of the RFQ, the drift has nothing to do with it. The Toutatis save the emittances at the cell end position.

Regards,

Didier

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Emittance growth at rfq end

Emittance growth at rfq end

Re: Emittance growth at rfq end

Re: Emittance growth at rfq end