Beam Test Apr 26 2012

Coil current vs Electron Beam Energy

Coil           En 
Current 
(Amp)          (MeV)
6.50 	 	3.49960871
15.25 	 	8.04790047
24 	 	12.5378648
33 	 	15.6004336

Preparation

[Check List]

1. Magnets (on/off)

2. Camera: (on/off) (Sync) (shielding)

3. Flags: (In/Out)

4. Farady Cup: hocked up?

5. Blank off for camera on?

6. Gas bottle for valve full?

7. Gas bottle for flags full?

15.6 MeV Setting

Quad Scan is done here with Q1.

Energy switch changed to low energy setting. Part of the cavity is grounded.

Energy Switch	Out (High En Range)
Dipole Coil Current	33
e- Beam Energy ()	15.6004336 MeV (mapping )
Solenoid 1	0 A
Solenoid 2	0 A
Gun Hor	0 A
Gun Ver	0 A
Output Hor	0.4 A
Output Ver	0.3 A
Rep Rate	6
Gun HV	8.99(Knob Setting)
Gun Grid Voltage	10 (Knob Setting)
RF frequency	2856.291 MHz
Modulator HV Power Supply	4.84 (Knob Setting)
RF macro Pulse Length (FWHM)	300 ns
Q1 (A)	0
Q2 (A)	0
Q3 (A)	0
Q4 (A)	0
Q5 (A)	0
Q6 (A)	0
Peak Current on FC 1 (45 deg)	88.8 mAmps
Peak Current on FC 2 (45 deg)	26.4 mAmps
Scope on FC 1	200 px
Scope on FC 2	200 px
Beam Spot	200 px

Gun has been up to air for 3 times. It could be oxidation, contamination. Or it could be gun died, less likely. Roasting the gun to burn off the contamination is an idea. Chad just roasted gun for with higher current, we saw gun current increased many times. We will leave roasted for one night.

En spread and En measurement

File name in Flash drive.

Quad Test

Tune HRRL

Tune to following settings, observe beam. Check if there is mis-steering by quadrupole magnet.

This tune used for quad scan at Mar 17 2011, tuned by Dr. Kim.

Solenoid 1	6.8 A
Solenoid 2	10.4 A
Gun Ver	-0.2 A
Gun Hor	+0.4 A
Output Hor	-1.4A
Output Ver	-0.5 A
Gun HV	+9.75 (Knob Setting)
Gun Grid Voltage	5.25 (Knob Setting)
RF frequency	2855.816 MHz
Modulator HV Power Supply	4.42 (Knob Setting)
RF macro Pulse Length (FWHM)	200 ns
Peak Current on FC	37.2 mAmps
Scope on FC
e- Beam Energy	14 MeV

Test mis-steering

Use OTR screen observe the beam. Turn all the quads off, except one at time. Change quad currents, see if mis-steering happens.

Quad	Is there mis-steering?	Beam images for different quad coil currents
Q1		200 px 200 px 200 px
Q2		200 px 200 px 200 px	Q3		200 px 200 px 200 px
Q4		200 px 200 px 200 px
Q5		200 px 200 px 200 px	Q6		200 px 200 px 200 px

Emittence Test (If time allows?)

Tune HRRL establish stable beam

1. Looking at the beam position on the screen and by the beam current on FC, try to align beam line. The goal is to center the beam on the screen, and maximize the FC charge as high as possible.

2. Reduced the mis-steering at the quadrupole by tuning steerers in the linac.

3. Optimize steerers, solenoids in linac to get a round electron beam shape and no steering at the quadrupole.

4. One good tune earlier for reference: [Tune HRRL]

10 MeV

Energy is set by bending the beam to dipole at specific current.

Set dipole current for 10 MeV, and bend the beam. Tune the beam energy, until we see peak current at the 45 degree Faraday cup.

Emittance measurement at 10 MeV

This is scan for 10 MeV beam. 40 mAmps peak current. Q1 is on, All other quads are off.

1) Scan from -5 Amps to 5 Amps. Increment at 0.2 Amps.

3) Name images by numbers start from 1. Then go on. Like: -5 Amp is 1, -4.8 Amp is 2, and so on til 5 Amp is named 51.

4) Scan multiple times from -5 to 5 Amps, and put them in different folders. Name folder by number, like 1, 2, 3 etc. After finishing one scan go back to -5 Amps. When going back take small steps (like 1 Amp), do not jump from 5 Amps to -5 Amps directly. After reaching back to -5, wait for few moment (like 10 s).

5) For each time, take back ground images. It should be done when RF is on and gun is off.

6) After the scan take a scope image for the current of the FC after the OTR screen. Lower the current, so the vacuum window do not heat up. This step is to check energy.