Mode 1: DC Beam
To set up magnetic field compensation, steering, focusing, with beam power at a safe level, without complications from bunching. Can use 300kV PS current as an overcurrent trip(?). Safe is < 10W (33uA), but screens can probably only take 1W (3uA).
- Alignment, compensation: Set up field compensation by finding the excitation that minimizes the steerer correctors while keeping beam centred on the BPMs. (Task set 1).
- Align and focus the beam. Dither solenoids to centre beam in solenoids. Solenoid settings and beam size is a first check on emittance. (Task set 2&4a,d,e).
- Energy spread measurement to diagnose 300kV PS ripple: Use slit or aperture-selected beam through the analyzer leg (ELBT1). Momentum resolution is 600 at 1mm dia. aperture.
- Transverse emittance measurement: Task Set 7.
- Check high power up to 1kW at high power beam stop? What to use for protection devices?
Mode 2: 650 MHz cw
- Grid studies - buncher off:
- Fast Faraday cup (FFC) in DB3 - activate the grid while looking at the FFC on axis. This gives a measure of bunch structure - delta t.
- Activate the grid while directing the beam through analyzer leg. This checks .
- Assume rf deflector available - coast beam through the analyzer leg while defining the energy by a horizontally defining slit at dispersed focus - adjust solenoid to focus selected beam at downstream profile - turn on rf deflector and scan phase to set amplitude and phase - set to zero crossing phase and measure time width as a function of grid parameters
- Grid studies - buncher on: Task Set 3, 4b, 4c.
- measure energy spread in beam as a function of grid parameters in analyzing leg
- Time spread measurement with rf deflector: Use a collimator to reduce the transverse emittance in the main leg (DB1A and DB1B horizontally defining v-slits). Use solenoid to produce parallel beam (maximizes beam through collimators). Measure beam width at DB3 (solenoids off) for emittance. Turn analyzer on and thread beam through dispersed focus slit. With rf deflector off look at beam on last box profile monitor and adjust solenoid for focus. Turn on rf deflector and find zero-crossing phase. Measure width of dispersed beam to get time spread.
Mode 3: 100 Hz pulsed
This will allow raising the charge per bunch without raising beam power. Pulses are as short as 3 to stay below 1W (1:3000 duty).
- Need to check with FFC and in the analyzer leg, that the pulse is uniform, with square edges.
- Investigate change to bunch length, energy spread, transverse characteristics, as charge per bunch raised. Repeat steps in mode 1 above.