Preparation for Phase 2 Damage Study

• Summary of phase 2 proposal (May 2008), for Terenuma-san, and slides for ATF Technical Board, 11-12 June 2008 .

Please comment and add updates

Overall aim is to benchmark FE modelling of shockwaves in frequency/amplitude regime close to that which would take place at ILC/CLIC.

• Competing constraints for tests at ATF2
  1. Determine range of ATF2 beam parameters that will cause shockwaves most similar to those at ILC/CLIC
     1. Fluka study plus FE model study
     2. To test FE model behaviour, need range of beam parameters or impact locations that would cause significantly different (and measurable) shock waves
  2. Range of beam sizes achievable at sample location in ATF2.
     1. Needs optics modelling and measurements with beam
     2. Accuracy of parameter measurement (proximity of wire scanner to sample?)
  3. Range of frequency/amplitudes which can be measured with VISAR
     1. Bench study similar to Neutrino Factory, with loudspeaker to induce high frequency oscillations in samples
     2. Start with sample/VISAR; repeat in vessel with realistic separation of optical head-sample; include viewport (transmission of 1550nm?)

VISAR Support Stand

I have ordered the following equipment from PI. This should arrive at the end of January 2009 and be plug and play with their software. It can also be controlled by lab view.

3 x M403.1DG Linear stage, 80mm wide, 25mm, DCmotor gearhead 3 x C863.10 Mercury™ DC motor controller, including power supply 1 x M403.AP2 Adapter plate M403/M404 Zmounting

Move to Birmingham for integration with labView vi by Mark (NKW will be at RAL/Coseners on 6 Feb.)

I will include all documentation in the attachments.

Timescale

• Need to perform bench tests with VISAR in UK first, ATF2 has no beam after mid-June 2009 until Oct 2009. May/June 2009?

• Visit to ATF2 Feb/March to test optics model, check readout of beamline instrumentation at ATF2?
  • Who would be able to travel? When?

Actions

• Radiation Safety Document for ATF2
  • We will be able to use a Ti alloy sample 4mm thick, see Summary of phase 2 proposal.

• Amplitude and frequency of vibration expected (see DamageTestProposals) What is the profile of the shock wave at the measuring surface of the collimator, how rapidly does it vary with distance along the surface, is it symmetric?

• VISAR
  • We measure at a single point with the VISAR. We should take readings at different locations along the sample from single shot operation at nominally the same charge and beam size to build up a picture.
  • The measured amplitude may differ from predictions e.g. because we are actually measuring at a different position relative to the beam impact.
  • We need to phase lock the VISAR head (on PI xyz stage) and sample manipulator to allow us to move the target sample
  • Pulse by pulse, we need to know accurately the impact position (precision determined by FE model predictions)

• Sample
  • Thickness, materials, geometries: assume Ti alloy, 4mm thick, circular disc
  • Inclusion of several wires (to one side?), of different thicknesses: open question, but no photon counter downstream, therefore little use. Assume we measure spot size with wire scanner upstream and extrapolate with optics model to sample location.
  • Current monitor or photon detection downstream for edge finding? No.

• Expected effects
  • How does mounting sample on manipulator and VISAR on stage affect vibration? Will test in UK

• Funding
  • Any hardware which we need should be purchased before end of March 2009.

(previous/out dated) Next Steps

Our two biggest challenges would appear to be getting the correct optics and finding a way to perform the test that satisfies the ATF radiation safety. I would suggest that before we start any major procurement or other planning exercises we run simulations based on the likely optics we can achieve. The plan for the simulations would be as follows:

James predicts the smallest beam size we are likely to achieve, taking the dispersion and emmittence values used on 29/02/2008 as well as the values from the earlier runs, this should give us a spread of beam sizes dependant on the beam conditions. If at all possible to get a round beam it makes the ANSYS/AUTODYN simulations a lot easier.

Luis takes the beam sizes from James as well as the likely charges and runs Fluka to give us the energy deposition, assuming a target of 0.6rl Ti-6Al-4V.

George takes Luis data and runs simulations on ANSYS/AUTODYN. Speak to Chris Densham or Richard Brownsword on the capabilities of the VISAR and see if it is likely that we will see any results. I would imagine we would want atleast 1 order of magnitude better resolution on the VISAR than what we expect to see from the simulation results.

-- GeorgeEllwood - 22 Jan 2009