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Wayne R. Meier Lawrence Livermore National Lab Heavy Ion Fusion Modeling Update - Spot Size Model Changes* ARIES Meeting April 22-23, 2002 * This work.

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Presentation on theme: "Wayne R. Meier Lawrence Livermore National Lab Heavy Ion Fusion Modeling Update - Spot Size Model Changes* ARIES Meeting April 22-23, 2002 * This work."— Presentation transcript:

1 Wayne R. Meier Lawrence Livermore National Lab Heavy Ion Fusion Modeling Update - Spot Size Model Changes* ARIES Meeting April 22-23, 2002 * This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

2 ARIES HIF Modeling - WRM 4/22/02 2 Summary At the previous meeting, I showed a new spot size model that included emittance growth in the accelerator due to voltage errors on the gaps and field errors in the quads. Another factor that contributes to emittance growth has now been developed: beam transport through the chamber. Also, the effects of photo-ionization of the main-pulse beams is now accounted for. This is a beneficial effect. Since these formulas were just received (4/16), they have not yet been fully implemented in the driver systems code.

3 ARIES HIF Modeling - WRM 4/22/02 3 Term for emittance growth in chamber has been added = dimensionless “shape” parameter ~ ½ Q c = “net” perveance in chamber d = focus length Previous version (similarly for  y ) New version with added term

4 ARIES HIF Modeling - WRM 4/22/02 4 Emittance growth in chamber (cont.)  q =1 to 2 when gas effects are small A = ion mass, amu For flibe simulations at n = 7·10 12 cm -3,  q = 2 is a good fit. Example: for A = 131, d = 6 m Q c d = 25 mm·mrad This will lead to significant spot size contribution: R spot > 25(mm)/  mrad) where  = focus half angle (typically 10-20mrad)

5 ARIES HIF Modeling - WRM 4/22/02 5 Factor for photo-ionization gives smaller main pulse beams For pre-pulse beams For main-pulse beams These relationship are preliminary and require more simulations

6 ARIES HIF Modeling - WRM 4/22/02 6 Next steps Complete code modification for spot size scaling Run case with new target parameters from Debbie Callahan (not quite ready yet) that include larger beam array cone angle Verify spot size requirements of this target can be met Determine target gain scaling based on new target design Propose new reference point design


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