Goals: Optimization of the IP. Verification of the llaser waist position and electron beam angle wrt. collision plane.
08h25 ThomX was started; Modulator, Frig, Laser
09h30 Chillers were started, cycling all magnets
RI-C1/PS/STR.06-H.01 is out of order. Fixed with the health check by killing the device server.
09h58 HV is 'ON'
10h20 RF Gun phase is 162 dg., Linac steerers H [0.52 -2.73], V [-228 2.70], Sect. phase is 211 dg., Sect. Att. is 2.55 dB, TL/BPM02 X=0, Charges (BPMs): - 111 pC, -111 pC, -123 pC, -123 pC
Receipt from 04/06/2025 17h11
10h29 Beam transported to the ring
10h30 The ring RF cavity did not start due to interlock on Pi, Pr, RF. Fixed
11h - 14h Optimization of the ring by using also MRSV. We have arrived @MRSV to the sigma_x = 16.4 pixels and sigma_y = 13.5 pixels.1 pixel = 41 um.
14h Operation with X-rays
We started withthe flux of 50 pA and optimize it till 350 pA (sometimes up to 400 pA). The vertical orbit is attached. The X-ray flux depends strongly on the tuning of the Linac and TL + injection. During the optimization we do not modify the Ring elements. By changing the vertical corrector in the TL, the flux was increased by 100 pA. To be understood.
The injected charge in the ring shows slow oscillations, same as the ICT signals in TL (see screenshots). From time to time the injection/charge starts to jump, sources (similar situation is with FPC laser)
Start of the vertical and horizontal scans. initial pos_Y = -1.24 mm
| N |
Pox_X |
Flux |
sigma_vert (FIT) |
Poistion of the max (FIT) |
Comments |
| 1 |
-1.641 |
|
116 |
-1.22 |
|
| 2 |
-1.341 |
|
122 |
-1.25 |
15h27 |
| 3 |
-1.041 |
|
133 |
-1.28 |
15h38 |
| 4 |
-1.941 |
|
128/ |
-1.15/ |
16h01 refaire 17h11 |
| 5 |
-2.241 |
|
128 |
-1.1 |
16h22 |
| 6 |
-2.5 |
|
131 |
-1.06 |
16h58 |
| 7 |
-1.74 |
|
117 |
-1.17 |
|
| 8 |
-1.54 |
|
126 |
-1.2 |
|
With these data we get ANGLE = 5.1 mrad
With the vert orbit Ring BPM we calculated the following: BPM3 =-2.62 mm pos. 3.93 m and BPM4 = 2.99 mm pos 5.074 m => ANGLE = 4.9 mrad
Very good agreement given the precision of the measurements.
Stability of the injector is very important during these measurements.
We made the quasi flat vertical orbit around IP ANGLE 0.09 mrad. As for now, for this vert. orbit, the flux is 3 times lower ~110-120 pA, despite different scans and attempts to inclrease it. Apparently, vert. orbit in SEXT is very important and in current configuration should be offset.
19h STOP THOMX
Astra simulation of the phase charge scan (see figure) shows that this is a convolution of the electron bunch generated by the laser pulse, since electrons cannot be generated at the negative field at the cathode. Therefore, the zero crossing is a cutting edge. The maximum acceleration corresponds to 48.5 degrees.
From the phase charge scan (see figures): Sigma1=1/0.462/1.4=1.5 dg. (morning), Sigma2=1/0.337/1.4=2.1 dg. (evening). But it seems that last one has satellite bunch.
|