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

IFT\P Overview of injection progress In-flight target steering has been achieved Can improve overall target injection accuracy (goal ±1 mm to ease beam steering) 1.5 m target fall Magnetic coils accelerate target upward Magnetic slingshot design calculations were done and support the concept’s feasibility Field contour

IFT\P In-flight target steering achieved with dropped targets ±3 kV steering electrode Mirror Target release Target charging Camera Laser 10 cm, 0.14 s 80 cm, 0.18 s 60 cm, 0.24 s 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)

IFT\P We integrated in-flight steering with tracking system for real-time trajectory correction Labview screen shot - details next slide…

IFT\P We integrated in-flight steering with tracking system for real-time trajectory correction Poisson spot X vs time (mm) Control signal  V i Steering voltage based on X position (Poisson spot’s centroid) and velocity updates each ~10 ms Y X Steering voltage Steering duration X&Y position trace

IFT\P Standard deviation of target placement accuracy (1D) decreased from 254 to 107 µm Much of remaining error is believed due to “curve ball” effect in air V 0 VActive Feedback v F ~0.1 mrad accuracy is similar to that needed for IFE Additional goal is ±20 µm at 0.5 m for FTF

IFT\P GA’s EMS Group calculations support Robson’s magnetic slingshot concept feasibility Conducting tube Shuttle S/C Coil Trigger coil Conducting tube provides centering force but induces drag on shuttle 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

IFT\P 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 Tune for integer number of half oscillation periods during acceleration 12 ms for minimum radial velocity Bertie’s analytical estimate = 8.6 ms for same assumptions * 4000 N/m => T = 12.5 ms This shows centering force is adequate

IFT\P Coil drag and power dissipated are significant but acceptable with sufficient tube conductivity Energy dissipated per target ~15 mJ in high conductivity case (0.075 W) Acceleration force = 81 N >> drag force 2.5  (Ωm) -1 corresponds to very high-purity cryogenic aluminum 2.86  10 9 (Ωm)  (Ωm) -1 Eddy currents in tube wall induce drag = P/v

IFT\P A 40 coil design results in a very smooth acceleration profile Z (mm) dB/dz (T/m) Z (mm) Magnetic Field B z (T) Acceleration (G’s) SC= Nb 3 Sn v f = 60 m/s

IFT\P Summary of injection progress In-flight target steering has been achieved Real-time trajectory corrections based on position measurement (v~5 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).