Target Injection Update

1
Target Injection Update

• Presented by Ron Petzoldt
• Neil Alexander, Landon Carlson, Lane Carlson, Dan
  Frey, Dan Goodin, Phan Huynh, Robert Kratz,
  Robert Stemke and Emanuil Valmianski
• San Diego HAPL meeting
• August 8-9, 2006

2
Overview of injection progress
Magnetic slingshot design calculations were done
and support the concepts feasibility
In-flight target steering has been achieved Can
improve overall target injection accuracy (goal
1 mm to ease beam steering)
Magnetic coils accelerate target upward
1.5 m target fall

Field contour
3
In-flight target steering achieved with dropped
targets
Key parameters Target charge (-0.1 nC), Target
mass (300 mg), 4 mm diameter Peak velocity (5
m/s), Steering field range (150 kV/m) Steering
range (2 mm)
4
We integrated in-flight steering with tracking
system for real-time trajectory correction
Labview screen shot - details next slide
5
We integrated in-flight steering with tracking
system for real-time trajectory correction
XY position trace
Poisson spot
Y
X
X vs time (mm)
Steering voltage
0.4 -
Steering voltage based on X position (Poisson
spots centroid) and velocity updates each 10 ms
0.2 -
0.0 -
-0.2-
-0.4 -
Control signal ?Vi
Steering duration
6
Standard deviation of target placement accuracy
(1D) decreased from 254 to 107 µm
0.1 mrad accuracy is similar to that needed for
IFE Additional goal is 20 µm at 0.5 m for FTF
0 V
Active Feedback
-1500 V
F
Much of remaining error is believed due to curve
ball effect in air
v
7
GAs EMS Group calculations support Robsons
magnetic slingshot concept feasibility
Conducting tube

• Magnetic slingshot concept advantages
• Non-contacting ferromagnetic shuttle
• No friction wear
• Centering force provided by conducting enclosure
• No sabot or gas turbulence
• Potentially very accurate
• No mechanical feedthroughs required into
  cryostat
• Powered via simple DC magnetic field

S/C Coil
Shuttle
Trigger coil

Conducting tube provides centering force but
induces drag on shuttle
8
Vector Fields calculations show centering force
in conducting tube leads to 1 oscillation period
Shuttle length 40 mm Shuttle radius 4
mm Carrier saturation 2.4 T Tube inner radius
8 mm
4000 N/m gt T 12.5 ms
Berties analytical estimate 8.6 ms for same
assumptions
Tune for integer number of half oscillation
periods during acceleration 12 ms for minimum
radial velocity

This shows centering force is adequate

9
Coil drag and power dissipated are significant
but acceptable with sufficient tube conductivity
Eddy currents in tube wall induce drag P/v

• Energy dissipated per target 15 mJ in high
  conductivity case (0.075 W)
• Acceleration force 81 N gtgt drag force
• 2.5?1011(?m)-1 corresponds to very high-purity
  cryogenic aluminum

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A 40 coil design results in a very smooth
acceleration profile
10
SC Nb3Sn vf 60 m/s
Magnetic Field Bz (T)
5
0
30
600
0 200 400 Z (mm)
dB/dz (T/m)
Acceleration (Gs)
20
400
200
10
0 150 300
Z (mm)
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Summary of injection progress

• In-flight target steering has been achieved
• Real-time trajectory corrections based on
  position measurement
• (v5 m/s)
• 1-D placement accuracy improved to 107 ?m (1?
  at 0.8 m standoff).
• Calculations support the magnetic slingshot
  concept
• Can achieve constant acceleration with a 40 coil
  design.
• Adequate centering force is provided by a
  conducting tube.
• Drag is acceptable with a sufficiently
  high-conductivity tube material (very high-purity
  aluminum).