Electron energy increase in a laser wakefield accelerator using up-ramp plasma density profiles

Constantin Aniculaesei, Vishwa Bandhu Pathak, Hyung Taek Kim, Kyung Hwan Oh, Byung Ju Yoo, Enrico Brunetti, Yong Ha Jang, Calin Ioan Hojbota, Jung Hun Shin, Jong Ho Jeon, Seongha Cho, Myung Hoon Cho, Jae Hee Sung, Seong Ku Lee, Björn Manuel Hegelich, Chang Hee Nam

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The phase velocity of the wakefield of a laser wakefield accelerator can, theoretically, be manipulated by shaping the longitudinal plasma density profile, thus controlling the parameters of the generated electron beam. We present an experimental method where using a series of shaped longitudinal plasma density profiles we increased the mean electron peak energy more than 50%, from 175 ± 1 MeV to 262 ± 10 MeV and the maximum peak energy from 182 MeV to 363 MeV. The divergence follows closely the change of mean energy and decreases from 58.9 ± 0.45 mrad to 12.6 ± 1.2 mrad along the horizontal axis and from 35 ± 0.3 mrad to 8.3 ± 0.69 mrad along the vertical axis. Particle-in-cell simulations show that a ramp in a plasma density profile can affect the evolution of the wakefield, thus qualitatively confirming the experimental results. The presented method can increase the electron energy for a fixed laser power and at the same time offer an energy tunable source of electrons.

Original languageEnglish
Article number11249
Number of pages7
JournalScientific Reports
Issue number1
Publication statusPublished - 2 Aug 2019


  • laser wakefield accelerator
  • plasma density
  • plasma density measurement
  • electron beam density

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