George Ellwood

1
ATF2 Testing

• George Ellwood
• Tuesday 16th September 2008

2
Concept
Use a short target 4mm length that will absorb
less than 0.3 of the beam energy. Using a VISAR
aligned to the far edge of the target it should
be possible to measure the velocity of the
surface which would be a way of checking the
accuracy of the modelling.
3
Geometry Mass of Hot Zone

• Assuming a 100µm diameter beam.
• For a simple analysis assuming that the beam
  energy is distributed evenly along the length of
  the target.

Please look at original spreadsheet
here http//www.eng-external.rl.ac.uk/ilc/051-Bea
m_Energy_Calcs.xls
4
Energy
Allowable energy deposition is 0.3 of total beam
energy. With this and the mass of the heated
zone from slide 3 this gives a temperature rise
of 84C.
5
Stress
6
Analysis

• A peak stress of 93MPa is below the dynamic
  elastic limit of the material and wouldnt cause
  a shock wave.
• It might be possible to measure a stress wave
  that is below the elastic limit of the material.

7
Autodyn
I created a simple axial-symmetric model in
Autodyn. This was 4mm long and 4mm
diameter. The heated zone was 100µm diameter
into which an initial energy of 44206.69 J/kg was
deposited.
Due to the small size of the model and the small
elements used I multiplied the distances by 1000
in order to get it to work with Autodyn, this can
be corrected for later and doesnt affect the
overall results.
8
Animation showing stress wave
9
Velocity at Surface
This graph has been adjusted to take into
account the conversion factor.