The OPAL Discussion Forum

[Nicole Neveu <nneveu AT hawk.iit.edu>]

Here is some more info on the PITZ issue:

The same file was run on V1.3.2 and V1.2.0. and in both cases OPAL was able to run to completion. The issue was with the results (RMS, emittance, etc). I will share my graphs in the dropbox. The results were incorrect in the newer version, and I was loosing particles at the end of the run. After some discussion with Steve, he thinks the issue might be that the space charge solver was not getting initialized correctly?

Also, those were some of my very first runs in OPAL. I may have made a mistake in running them or in post processing?

Thanks,

Nicole 

On Wed, Aug 12, 2015 at 3:00 PM, Nicole Neveu <nneveu AT hawk.iit.edu> wrote:

Hello,

I've added Christof to the dropbox, and yes 3 &4 are related to the thermionic gun.

I will add the PITZ gun to the folder as well.

Thanks,

Nicole

On Wed, Aug 12, 2015 at 2:53 PM, Adelmann Andreas (PSI) <andreas.adelmann AT psi.ch> wrote:

Hi Nicole I cc to the mailing list and Christof. Can you also invite him to the Dropbox folder. 

Christof is one of the main developer and is in charge of the next release.

@Christof can you check the PITZ gun problems from 1.2.0 to 1.3.2 and advise Nicole.

Point 1: if you emit particles the image charges are on otherwise off. If the bunch is sufficiently far away

the image change is turned off. I need do check the distance.

The points 3 and 4 is related to the thermionic case correct?

A

 

------
Dr. sc. math. Andreas (Andy) Adelmann
Staff Scientist
Paul Scherrer Institut WBBA/219 CH-5232 Villigen PSI
Phone Office: xx41 56 310 42 33 Fax: xx41 56 310 31 91
Phone Home: xx41 62 891 91 44
-------------------------------------------------------
Friday: ETH CAB H 85.1  +41 44 632 75 22
============================================
The more exotic, the more abstract the knowledge, 
the more profound will be its consequences.
Leon Lederman 
============================================

On 12 Aug 2015, at 20:18, Nicole Neveu <nneveu AT hawk.iit.edu> wrote:

Andreas,

Thanks for the email and info. I've uploaded my files to a dropbox folder, since the 3D field map is too large to send over email.

Here is my next round of questions:

1. How is the image charge calculation handled? Is it turned on / off within the space charge solver?

2. While benchmarking the PITZ gun on V 1.3.2-3, it seemed I was having some space charge issues. That's why I am using V 1.2.0. Should I switch over to a newer version now, or continue using V 1.2.0?

3. With my current input file, I am loosing 99% of the particles. Based on previous simulations done in Parmela with a similar gun, I would expect to loose 80% of the particles (paper in dropbox).

4. In photoinjector simulations I ran on OPAL, I had to run with the injection phase close to the region of max energy gain, or my run would crash. Since we are emitting over all 360 degrees, does the phase matter?

Thanks again for all your help!

Nicole

On Wed, Aug 12, 2015 at 12:36 AM, Adelmann Andreas (PSI) <andreas.adelmann AT psi.ch> wrote:

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 

------
Dr. sc. math. Andreas (Andy) Adelmann
Staff Scientist
Paul Scherrer Institut WBBA/219 CH-5232 Villigen PSI
Phone Office: xx41 56 310 42 33 Fax: xx41 56 310 31 91
Phone Home: xx41 62 891 91 44
-------------------------------------------------------
Friday: ETH CAB H 85.1  +41 44 632 75 22
============================================
The more exotic, the more abstract the knowledge, 
the more profound will be its consequences.
Leon Lederman 
============================================

On 05 Aug 2015, at 18:53, Nicole Neveu <nneveu AT hawk.iit.edu> wrote:

Nicole Neveu  

Argonne National Lab