The OPAL Discussion Forum

["Adelmann Andreas (PSI)" <andreas.adelmann AT psi.ch>]

Hello Nicole

Andreas,

Yes, I was able to simulate AWA's photoinjector (with version 1.2.0), and we had great agreement with ASTRA simulations. I ran many different cases without major issues, so that was encouraging.

great, thanks for the update. 

However, I haven't had as much luck with the thermionic case (learning curve I would say), here is some relevant info: 

- The gun is RF 

- 75 MV/m max field

- Current density = or > 10 A/cm^2

- 3.0 mm cathode

- field map is 3D

Questions: 

1. Will OPAL allow distributions with hard cut offs? i.e. TRISE = TFALL = 0. Pasted below is my best guess at a cylindrical distribution with radius 3.0mm. How does it look? 

Dist:DISTRIBUTION, DISTRIBUTION = FLATTOP,

SIGMAR = 0.003, 

TRISE = 0,

TFALL = 0,

TPULSEFWHM = ID_FWHM_TIME_FLAT / 1.0e12,

CUTOFFLONG = 3.0,

NBIN = 9,

EMISSIONSTEPS = 10,

EMISSIONMODEL = ASTRA, 

EKIN = 0.2,

EMITTED = True,

WRITETOFILE = False;

I browsed through the src code and could not see a immediate problem with TRISE/FALL = 0,. 

2. I've tried using the BOUNDPDESTROYFQ option to control lost particles. I get this error: 

OPAL{+0}> *** Parse error detected by function "Object::parse()"

OPAL{+0}> *** in line 3 of file "TGDistTest1.in" before token "=":

OPAL{+0}>     OPTION,BOUNDPDESTROYFQ=10;

OPAL{+0}>     Object "" has no attribute "BOUNDPDESTROYFQ".

That is a maybe problem of 1.2.0.  Should be fixed later versions. Will have a closer look

later.

3. 've seen these warnings a lot, even when running my AWA files. What do they mean?

Warning{+0}> reduce: there was nothing to reduce, since the masks were all false.

Warning{+0}> Could not set total charge in PartBunch::setCharge based on getTotalNum

At the very begin there are no or only very few particles in the simulation, hence you see the 

above messages. 

----------------------------------------

Warning{+0}> Marker not implemented yet!

Warning{+0}> Marker not implemented yet!

The parser is inserting in a very per-curlier way Marker (a la MAD) that are not implemented yet.

Maybe it is easier if you send the input file and field map so I can have a look at it.

Cheers Andreas 

Thanks!

Nicole

On Wed, Aug 5, 2015 at 12:12 PM, Adelmann Andreas (PSI) <andreas.adelmann AT psi.ch> wrote:

Hi Nicole 

I am a new user of OPAL, and I've been simulating photoinjectors. When I first started it was a great help to look at the PITZ gun file that Steve Russell passed along. 

Great, I hope you had success !

Now, I would like to simulate a thermionic gun. I think making the switch would mainly consist of adjustments to the beam distribution, and of course new field files. I have a good idea of where to start based on chapter 11 of the manual, but it would be great if I could see an example input file. Do you guys know of anyone who has simulated thermionic guns in OPAL? 

No I do not know if anyone simulated a thermionic gun. Would that be a DC gun? What are the parameters? Basically you are right you need to come up with a realistic

beam distribution, OPAL can not simulate the emission process.

Cheers Andreas 

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Dr. sc. math. Andreas (Andy) Adelmann
Staff Scientist
Paul Scherrer Institut WBBA/219 CH-5232 Villigen PSI
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On 05 Aug 2015, at 18:53, Nicole Neveu <nneveu AT hawk.iit.edu> wrote:

Nicole Neveu  

Argonne National Lab