[Tgun] GTS Photogun Beam Structure

[Riad Suleiman]

For the micro structure, we started at 374.25 MHz but will change to 499 
MHz later this summer to test a TE011 cavity. The micro structure 
repetition rate can vary - but must match any RF components on beamline.

When we switch to the high power laser to generate nC bunches, we will 
run at 1-20 Hz with a single micro bunch of about 50 ps. At this time, 
we have to resolve any issues related to diagnostics.

Riad.


On 06/22/2018 09:25 AM, Matt Poelker wrote:
> But you don't mind that the tgun will pulse at a different rep rate, 
> right?
>
>
> On 6/22/2018 9:22 AM, Riad Suleiman wrote:
>> Hello,
>>
>> These are the GTS beam structures used with the photogun:
>>
>> 1. CW Beam for high current runs: Micro structure of 374.25 MHz, 50 ps.
>>
>> 2. Tune Beam for Harp: Macro structure of 60 Hz, 250 us. The nominal 
>> average beam current during a harp scan is 100 nA. This gives a peak 
>> current during the 250 us of about 0.1*1/(60*0.000250) = 6.7 uA.
>>
>> 3. Viewer Limited Beam for Viewers (YAG): Macro structure of 60 Hz, 4 
>> us. The nominal average beam current on viewer is 2 nA. This gives a 
>> peak current during the 4 us of about 0.002*1/(60*0.000004) = 8.3 uA.
>>
>> Notes:
>> 1. We use a Beam Sync signal that goes to the laser table to generate 
>> the beam macro structure. This signal also goes to the harp to 
>> trigger the readout. Another copy goes to the camera of the third 
>> viewer. Of the three viewers, only the third one has a camera with an 
>> external trigger. We are planning to run at 10 Hz this summer and 
>> will find out if there is any issues related to running at 
>> frequencies other than 60 Hz.
>>
>> 2. The Harp ADC records only one sample at approximately the middle 
>> point of the 250 us beam pulse. Thus, reducing the width of the Tune 
>> Beam may require other changes to Harp readout.
>>
>> Yours,
>> Riad.
>>
>
>
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