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Rutherford Appleton Laboratory

laser. R. l s. Three mechanisms interact to cause ion acceleration in PW laser interactions. Rutherford Appleton Laboratory.

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Rutherford Appleton Laboratory

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  1. laser R ls Three mechanisms interact to cause ion acceleration in PW laser interactions Rutherford Appleton Laboratory • Relativistic electrons expelled by the ponderomotive pressure of light wave. To overcome the attractive electric field of the ions, Ee > Ec . The Coloumb energy Ec is approximately • Ec 2 2 ne2lsR • Later the ions move due to Coloumb repulsion. • Ei 4 2 ne2R2 • Inductive electric field caused by the rapid change in the B field that accelerates ions and decelerates electrons. The energy gained by this process is • Ei 8 e2n R2

  2. 3D computer simulations of ion acceleration process Rutherford Appleton Laboratory Sophisticated 3D simulations performed by Prof. S.Bulanov and co-workers has revealed that for linear polarisation case the ion energy is px = 0.61mic Conclusion: at intensities 31021 Wcm-2, ~1012 protons are accelerated with energies of several hundred MeV

  3. Prospects for GeV proton acceleration using PW lasers Rutherford Appleton Laboratory a02 Il2  a0Il2 PIC simulation T.Zh.Esirkepov et al JETP Lett 70, 82 (1999) PIC simulation S.V.Bulanov et al JETP Lett 71, 407 (2000)

  4. Accelerating gradients 200 TeV/cm at 1026 Wcm2 Wakefield acceleration Rutherford Appleton Laboratory The energy gain over the interaction length in a plasma wakefield is When Il2 >> 1018 Wcm-2mm2, the radiation pressure is so large nearly all electrons are expelled from the photon wave-envelope, generating a “snow-plough” in which the electron momentum gain is provided the laser pulse fully interacts with the plasma (i.e. not diffracted)

  5. 527 nm Nd:glass SHG 1000ps 3400 J 3400 J 3400 J 41 % 44 % 46 % h 0.2 mJ 4 J KDP KDP KDP LBO LBO 4452 J 0.8 cm 20 fs seed laser stretched to 400 ps 3.8 cm 1.1 cm 1.4 cm 1.5 cm Output signal and pump intensity profiles Intensity profile after compression 100 PW (0.3 J/cm2) Ideas for EW lasers (Dr I.N.Ross) Rutherford Appleton Laboratory

  6. Future Upgrade Options • Given Some Technology Development • SHG Pump Dielectric Gratings 1μm Output 50cm KDP F/1 Focusing 0.3 EW 1025 W/cm2 Rutherford Appleton Laboratory • THG Pump Dielectric Gratings 0.5μm Output 50cm KDP F/1 Focusing 0.6 EW 1026 W/cm2 • Multi OPCPA >1 EW >1026 W/cm2

  7. Summary Rutherford Appleton Laboratory • The VULCAN PW upgrade is nearly completion - first experiments to university users scheduled November 2002 - laser wakefield accelerator studies • >100 MeV protons and >1GeV heavy ions expected • Future upgrades to multi-PW levels are being actively pursued • The CLF is investigating new designs for average and peak power lasers required for accelerator and fusion applications

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