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Re: [Opal] Question about setting solenoid, and TWS cavity

Chronological Thread 
  • From: Christof Metzger-Kraus <christof.j.kraus AT>
  • To: sykim12 AT
  • Cc: opal AT
  • Subject: Re: [Opal] Question about setting solenoid, and TWS cavity
  • Date: Thu, 2 Aug 2018 14:23:22 +0200
  • Authentication-results: localhost; dmarc=pass

Hi Seong-Yeol,

1) per default Opal normalizes the on-axis field of the provided field map. The value that you provide as KS in the input file is then the maximum field strength on-axis. 

I'm not sure whether the manual is correct about the unit of KS. I'll have to check first. 

2) could you send me the input file and the field maps? 


<sykim12 AT> schrieb am Do., 2. Aug. 2018, 13:49:
Hello, This is Seong-Yeol Kim of BE-RF Group at CERN. I am Ph.D Student in
Ulsan National Institute of Science and Technology in Korea, and now I am
working at CERN.

1. Concerning the OPAL code, I am learning how to use it for simulating gun
section. However, first I am wondering how to put the specific number for
strength. In the manual, solenoid field strength KS is defined by partial
derivative of B and has a unit of [T/m]. Does it mean that it is an average
value of the field ?
(for instance, KS = <B> / L where L is solenoid length, and <B> is average
field value defined by 1/L * int( B ); int means integral over solenoid
If not, please let me know what the strength KS of the solenoid field in OPAL,
and how to get the value with unit of [T/m].

2. I am trying to put travelling wave structure as a booster after gun
section. Following the manual I put numbers for mode (1/3=2pi/3), number of
cells, under auto-phase.
And the file I have for TWS is actaully ASTRA format, so I modified it for
OPAL format with the option 'AstraDynamic'. However, even if the number of
cells is 30,
energy gain is very different from the on using ASTRA. (about 6 MeV in OPAL,
and about 18 MeV in ASTRA). Also another problem is that, when I run the
there are some messages 'ParallelTTracker > * Deleted ~ particles, remaining ~
particles', and 'The reference particle hit an element' near the position of
TWS, and simulation is stopped automatically.
Could you please let me know how to fix this problem?

Thank you for your help!

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