9.4.2.0 Spatio-temporal alignment procedure

Initial Spatial overlap between LPL, VISAR and X-rays

• This procedure assumes that
  • the beamline is aligned up to yag3
  • the slits are aligned to the beam
  • the yag at TCC has been prealigned with the help of Questar 2 as well (for maximum accuracy) and the pin (the pin is used to measure the LPL spot size and set the plan of interaction)

• Go to the yag at TCC

  op.yag()

• Remove the hutch Be CRL

• Close slits 4 to 50 mic

  op.slit4.move(0.05)

• Set a cross on Questar 1 screen and write down the X and Y positions in the preset spreadsheet of the experiment

• Close the pulse picker and reinsert the Be CRL

  op.pp.close()

• Move to the pinhole

  op.pinhole()

• Tweak the position of the pinhole until it is centered on the cross

  x.hex_y.tweak(0.02)
  x.tgx.tweak(0.02)

• Save the new pinhole position

  op.pinhole_s()

• Move back to the yag

  op.yag()

• Send the VISAR laser with event code 43 and enable the trigger
• Confirm that the focus of the VISAR provides a sharp and round image on any VISAR cameras (Visar gige 1 and 2)

• Tweak the focus of the visar position accordingly (50 mic steps is good enough)

  op.visar_z.tweak(0.05)

• Turn off the VISAR trigger

• Prepare the system to check the front alignment of the drive lasers

  op.check_front_alignment()

• Check spatial overlap of the drive beams ABEF and GHIJ successively by centering the scattered signal on the cross of Questar 1 screen

  op.TTL_shutter.Toggle("openABEF")
  op.TTL_shutter.Toggle("closeGHIJ")
  x.lpl_west_x.tweak(0.05)
  x.lpl_west_y.tweak(0.05)
  op.TTL_shutter.Toggle("closeABEF")
  op.TTL_shutter.Toggle("openGHIJ")
  x.lpl_east_x.tweak(0.05)
  x.lpl_east_y.tweak(0.05)

• Record each positions of the VISAR and drive lenses in the experiment spreadsheet

Initial Temporal overlap between LPL and X-rays

• go to Ti sample

  op.ti()

• remove the Be CRL

• open slit4 to 400 mic

  op.slit4.move(0.4)

• set full X-ray transmission

  op.SiT(1)

• open the pulse picker

  op.pp.open()

• Open the TCC scope

  op.scope_timing_remote()

• Set the EVR of the scope to 10Hz

  op.lpl_check_timing("10Hz")

• Set channel 2 to 2 or 5 mV/div
• Confirm that the X-ray pulse is seen around 60 ns.
• Average over 100 sweep and save the trace on M2 (from C2)
• Set the sweep averaging back to 1

• Close the pulse picker

  op.pp.close()

• Insert the filter in front of Questar 1

  op.fw(num=1, position=3)

• Set the laser pulse shape to the timing shape

  op.LPL.psmenu()
  LXX
  op.LPL.psefc10Hz()

• Send the 10Hz LPL (enable the trigger of the ns slicer) on target at full energy

  op.HWPon('all', set_T=1.0)

• Set the channel 2 to 10 mV/div
• Confirm you see a trace on C2
• Average over 100 sweep and save the trace on M3 (from C2)
• Set the sweep averaging back to 1
• Take a screenshot and post it to the elog
• Set the channel 2 to 1V/div

• Set the scope to single shot trigger

  op.lpl_check_timing("single")

• Further fine timing can be done by using a LiF coated window
  • Move to the appropriate target
  • Confirm Be CRL are inserted in the beamline

  • Set the timing of the drive to 0

    op.nstiming.mv(0e-9)

  • Confirm that the streak window have zero offset in the window size requested

    op.streak_window(visar=1, window=20, offset=0)
    op.streak_window(visar=2, window=20, offset=0)

  • Take a single refence only shot to observe the change in reflectivity at the arrival time of the X-rays

    op.ref_only(
    	xray_trans=1,
    	xray_num=1,
    	shutters=False,
    	dark=0,
    	daq_end=True,
    	calibrant="",
    	rate=1,
    	visar=True,
    	save=True,
    	slow_cam=False
    )

  • To double check, confirm timing at another step

    op.nstiming.mv(10e-9)
    op.ref_only(
    	xray_trans=1,
    	xray_num=1,
    	shutters=False,
    	dark=0,
    	daq_end=True,
    	calibrant="",
    	rate=1,
    	visar=True,
    	save=True,
    	slow_cam=False
    )

  • Fine tune the timing is the X-ray trace is not where it is expected using the nstiming.mv function accordingly.

Check Spatial overlap between LPL, VISAR and X-rays on target

• Start by moving to the desired target (refer to the python manual here for details on the arguments)
  

  op.move_to_target(config="colinear", frame_cfg=[1, "F1", 1, "F2", 1, "F3"], frame=2, target="A2")

• Continue by checking the alignment of the drive lasers

  • Set the system in a mode where the laser energy is minimum, the filter is removed from questar 1 and the trigger is enabled

    op.check_front_alignment()

  • Confirm you see a scattering signal close to the X-ray cross (342, 561)

  • Move the hexapod X axis to center the beams on the cross and produce a round scattering signal (steps of 50 mic is good)
    

    x.hex_x.tweak(0.05)

• Continue by checking the alignment of the VISAR system

  • Adjust the VISAR Z axis to make sure the image is round and sharp (could be set to the value by using the right equation as well). Steps of 50 mic is good.
    

    x.visar_z.tweak(0.05)

  • Alternatively, move the Z value by exactly the thickness of the ablator + material of interest and add the change in position due to the visar window. To calculate the change use the following command

    op.visar_window_compensation(material="LiF", thickness=400e-6)

Take reference images with VISAR and/or X-rays

• For 5 references with VISAR and X-rays (at 20% max)
  

  op.ref_only(
  	xray_trans=0.2,
  	xray_num=5,
  	shutters=False,
  	dark=0,
  	daq_end=True,
  	calibrant="",
  	rate=1,
  	visar=True,
  	save=True,
  	slow_cam=False
  )

Take a driven shot with the LPL

• For a driven shot at full energy (lpl_ener=1.0), with X-rays arriving 5 ns later (timing=5.0e-9) at full intensity (xray_trans=1) use the following command
  

  op.optical_shot(
  	shutter_close=[1, 2, 3, 4, 5, 6],
  	lpl_ener=1.0,
  	timing=5.0e-9
  	xray_trans=1,
  	xray_threshold=0.2,
  	save=True,
  	daq_end=True,
  	auto_trig=True,
  	auto_charge=True,
  	visar=True,
  	debug=False,
  	ps_opt=True
  )