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Ulsan National Institute of Science and Technology

Efficient acceleration of monoenergetic proton beam by sharp front laser pulse review. 2012. 6.18. Y.K KIM. Toward a World-Leading University. Ulsan National Institute of Science and Technology. 1D SIMULATION. • There is difference between paper(left) and my calculation(right). •

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Ulsan National Institute of Science and Technology

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  1. Efficient acceleration of monoenergetic proton beam by sharp front laser pulse review 2012. 6.18 Y.K KIM Toward a World-Leading University Ulsan National Institute of Science and Technology

  2. 1D SIMULATION • There is difference between paper(left) and my calculation(right). • ( •

  3. 1D SIMULATION • There is difference between paper(left) and my calculation(right). • ( •

  4. Simulation Set Up • 2D CP trapezoidal pulse(temporal) four-order super-Gaussian(transversely) Domain: 100μm x 60μm Absorbing boundary 10 macroparticles in each cell (1920000) Initial memory = 44GB • 1D CP trapezoidal pulse

  5. Simulation Set Up trapezoidal pulse(temporal) four-order super-Gaussian(transversely) PML is set up

  6. Simulation Set Up • 2D trapezoidal pulse(temporal) four-order super-Gaussian(transversely) Domain: 100μm x 60μm → 80μm x 60μm Target position = 50μm → 30μm Flat pulse length = 20 Rising time = 10%~90% (ref: wiki) Tup+Tdown = 25T (my assumption) ex) Tup=1T →Tdown=24T, Tup=3T→Tdown=22T Total pulse duration = 51.25T Left PML set up time = 50T (my mistake) Absorbing boundary 10 macroparticles in each cell (1920000)

  7. • t=95T • • t=95T • • t=72T • • t=95T • • t=72T • Reproduce

  8. • t=95T • • t=72T • • 0.25dt • t=72T • Reproduce

  9. Energy [MeV] • Rising time 에 대한 수정을 하고 시뮬레이션을 하였습니다. 그 결과 논문과는 다르게 1Tup 에서 결과가 더 좋게 나왔습니다. 명훈이 형님이 time step 을 courant condition 의 절반으로 줄이니까 결과가 다르다고 하셔서 저도 time step 을 줄여 보았습니다.

  10. • t=52.5T • • 0.25dt • t=51T • • 0.5dt • time step 을 줄여보니논문과 결과가 비슷하게 나오고 있습니다. • |y|=10 이내의 proton energy distribution [MeV]

  11. • time step 을 0.25배로 더 줄여보니 결과가 더 정확하게 나오는 것으로 보입니다. 어떻게 time step을 결정해야 할 지 아직은 모르겠습니다. 우선은 courant conditiontime의 0.25배로 시뮬레이션들을 다시 하려 합니다… 0.25dt 0.5dt

  12. • t=84T • t=72T • • 0.5dt • 0.3T cutoff Tup=3.3T 인 최적값에서커브드 펄스를 사용하기 보다는 Tup=24T, 16T 정도인 펄스에서 적당히 cutoff 시켜가며 (3T, 6T, 12T, 18T) cutoff 지점을 찾고, 그 지점에서 펄스에 모양을 주기로 하였습니다. 72T 84T

  13. • t=90T • • 6T cutoff • t=72T • • 0.5dt • 6T cutoff cutoff 0T 6T 24T • t=72T • • 0.5dt • 12T cutoff • t=90T • • 12T cutoff 0T 12T 24T

  14. • t=90T • • 6T cutoff • t=72T • • 0.5dt • 3T cutoff cutoff 0T 24T 3T • t=72T • • 0.5dt • 18T cutoff • t=90T • • 18T cutoff 0T 18T 24T

  15. • t=72T • • 0.5dt • t=90T 6Tup 3Tup 24Tup 12Tup 18Tup cutoff cutoff 0T 0T 3T 6T 24T 24T 18T 0T 0T 0T 12T 12T 24T 24T 24T

  16. • Tup=3.3T • cutoff at 3T • cutoff at 3T • Tup=24T • Optimum (paper)

  17. • Gaussian pulse and shaped pulse • Parabolic focus 2um • Parabolic vertex 0.5sigma • Super Gaussian pulse and shaped pulse • Parabolic focus 9um • Parabolic vertex 0.5sigma 슈퍼가우시안 빔을 포물선 형태로 바꾸었을 때 transverse 방향으로 빔의 에너지 비율이 크게 증가하지 않는다. 빔 shaping 효과를 잘 관찰하기 위해서는 Gaussian 빔을 이용해야 할 것 같음. Ref) BulanovPRE 78 026412 (2008)

  18. • t=90T • Gaussian pulse • t=72T • Gaussian pulse • t=72T • Shaped pulse • t=90T • Shaped pulse

  19. • t=90T • t=72T Shaped pulse Shaped pulse Gaussian pulse Gaussian pulse Cutoff at 3Tup • t=81T • t=72T Cutoff at 3T Shaped pulse Shaped pulse 3.3Tup

  20. paper • 1Tup • 0.5dt • 0.1dt • 0.1dt • 0.5dt

  21. • t=90T • t=72T Shaped pulse, 2um Shaped pulse, 2um cutoff pulse Shaped pulse, 3um cutoff pulse Gaussian pulse Cutoff pulse: 최대 에너지가 높다 Shaped pulse(2um): 빔 차지량이 많다. Shaped pulse(3um): Gaussian 과 2um pulse 사이의 특성을 보인다. -> shaped pulse (1um) 시뮬레이션을 통해서 2um 부근이 optimum 임을 확인해 보는 것이 좋을 듯

  22. • 60T • 0.5dt • 60T • 0.1dt

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