Chopper wheel
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Chopper wheel Rotates at 100 Hz and contains a timing photodiode to signal position on each turn. A slot cut in the disc passes a 130 ms laser pulse train Stanford DG535 (Repetition Rate) This unit sets the macropulse repetition rate by inhibiting the 100 Hz timing signal from the chopper wheel Quantum Composer 8-Channel timing unit This unit is triggered by the Repetition Rate DG535, and takes a clock input from the 81.25 MHz RF reference. On triggering, it waits for the next RF clock cycle, then cascades trigger signals to the Mechanical Shutter (selecting a specific macropulse), and to the Macropulse Length DG535 to set the macropulse length. Additional trigger signals are provided to the rack room and the TW laser. Trig A B C D E F G H Mechanical Shutter The mechanical shutter selects specific macropulses from the 100 Hz macropulse train to define the 1, 2, 5, 10 or 20 Hz repetition rate Stanford DG535 (Macropulse Length) This unit provides trigger to the Pockels cell driver to define the macropulse length Streak Camera TW Laser 1 7 Rack Room Sync A B C D T Pockels Cell Driver 3 4 81.25 MHz AΠB
description
Stanford DG535 (Repetition Rate) This unit sets the macropulse repetition rate by inhibiting the 100 Hz timing signal from the chopper wheel. Quantum Composer 8-Channel timing unit This unit is triggered by the Repetition Rate DG535, and takes a clock input from the 81.25 MHz RF reference. - PowerPoint PPT Presentation
Transcript of Chopper wheel
Chopper wheel
Rotates at 100 Hz and contains a timing
photodiode to signal position on each turn. A slot cut in the disc
passes a 130 ms laser pulse train every turn.
Stanford DG535(Repetition Rate)
This unit sets the macropulse repetition
rate by inhibiting the 100 Hz timing signal from the
chopper wheel
Quantum Composer 8-Channel timing unit
This unit is triggered by the Repetition Rate DG535, and takes a clock input from the 81.25 MHz RF reference.
On triggering, it waits for the next RF clock cycle, then cascades trigger signals to the Mechanical Shutter
(selecting a specific macropulse), and to the Macropulse Length DG535 to set the macropulse length.
Additional trigger signals are provided to the rack room and the TW laser.
Trig
A B C D E F G H
Mechanical Shutter
The mechanical shutter selects specific macropulses from the 100 Hz macropulse train to define the 1, 2, 5, 10
or 20 Hz repetition rate
Stanford DG535(Macropulse Length)
This unit provides trigger to the Pockels cell driver to define
the macropulse length
Streak Camera
TW Laser1
7
Rack Room
Sync
A B C D TPockels Cell Driver
34
81.25 MHz
AΠB
Quantum ComposersTiming Unit Settings
Sync. Channel Width Delay Pol Output ModeWait
Pulses Driving
Alternative for ‘other’ chopper sensor location
T0 'A' 100 us 0 ms Act high TTL/CMOS Normal 0 Main RF trigger (via #1 on roof feed-thru box)
‘A’ 'B' 4 ms 24. ms Act high TTL/CMOS Normal 0 Mechanical shutter 4.5 ms / 4.0 ms
T0 'C' 150 us 0 Act high TTL/CMOS Normal 0 Not used (suspected faulty)
T0 'D' 150 us 7.06 ms Act high TTL/CMOS Normal 0 Trigger to DG535 7.085 ms / 150 ms
T0 'E' 100 us 7.00 ms Act high TTL/CMOS Normal 0 Feed to rack room (via #7 on roof feed-thru box)
T0 'F' 100 us 7.06 ms Act high TTL/CMOS Normal 0 EMMA RF System Trigger
T0 'G' 100 us27.56
889 ms Act high TTL/CMOS Normal 0 Streak Camera trigger
T0 'H' 91 ms 1.1 ms Act high TTL/CMOS Normal 0 Macropulse repetition rate (setting for 10 Hz)
Gate: Mode (Chan Menu) –Level - 2.50 V;
Clock: Rate - 81.25 MHz; Level - 0.1 V; Ref. out - To pulse; Ext. Opt. - Force OFF; T0 clock rate - 0.010000000
Trig: Mode – Triggered; Level – 1.00 V; Edge – Rising Edge
Incorrect timing settings which do not drive EMMA RF correctly due to a 20 ms offset in the main R trigger, changed 2011 02 25
Quantum ComposersTiming Unit Settings
Sync. Channel Width Delay Pol Output ModeWait
Pulses Driving
Alternative for ‘other’ chopper sensor location
T0 'A' 140 us 20.31 msAct high TTL/CMOS Normal 0 Main RF trigger (via #1 on roof feed-thru box)
‘A’ 'B' 4 ms 24.0 msAct high TTL/CMOS Normal 0 Mechanical shutter 4.5 ms / 4.0 ms
T0 'C' 150 us 0Act high TTL/CMOS Normal 0 Not used (suspected faulty)
T0 'D' 150 us 26.37 ms *Act high TTL/CMOS Normal 0 Trigger to DG535 7.085 ms / 150 ms
T0 'E' 100 us 26.41 ms **Act high TTL/CMOS Normal 0 Feed to rack room (via #7 on roof feed-thru box)
T0 'F' 100 us 7.01 msAct high TTL/CMOS Normal 0 EMMA RF System Trigger
T0 'G' 100 us 27.56889 msAct high TTL/CMOS Normal 0 Streak Camera trigger
T0 'H' 95 ms 1.1 msAct high TTL/CMOS Normal 0 Macropulse repetition rate (setting for 10 Hz)
Gate: Mode (Chan Menu) – Level - 2.50 V
Clock: Source Ext. w/PLL; Rate - 81.25 MHz; Level - 0.1 V; Ref. out - To pulse; Ext. Opt. - Force OFF; T0 clock rate - 0.010000000
Trig: Mode – Triggered; Level – 1.00 V; Edge – Rising Edge
* = Value changed from 27.37 ms to 26.37 ms on May 23 following shutdown work.** = Value changed from 27.31 ms to 26.41 ms (noted on 28/8/12 – not sure when change was actually made)
New timing settings established to drive EMMA RF correctly using timingsensor located on the left-hand side of the chopper wheel, set 2011 02 25
DG535 Unit Settings:Macro Pulse Length (Pockels Cell)
Channel Delay Driving
'A' A = T + 0.000 358 008 Trigger onset delay
'B' B = A + 0.000 000 014 Macro Pulse length (example shows 10 ns)
'C' C = A – 0.000 000 150
'D' D = C + 0.000 001 000 Trigger to Pulse picker Pockels cell
T0 Trigger to PC for PCO camera or streak camera
Trig: Ext.; Threshold = +0.16 V; Slope (+/-) = +; Trigger term = High Z
Output: AB; AB & -AB Loads = High Z; AB: TTL
Values correct, as of October 25th Channel ‘A’ adjusted slightly to capture beam following shutdown work
