Intra-pulse transition between ion acceleration mechanisms in intense laser-foil interactions

Journal Article · Wed Jun 15 00:00:00 EDT 2016 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4954654· OSTI ID:22598941

Padda, H.; King, M.; Gray, R. J.; Powell, H. W.; Gonzalez-Izquierdo, B.; Wilson, R.; Dance, R. J.; MacLellan, D. A.; Butler, N. M. H.; Capdessus, R.; Stockhausen, L. C. ^[1]; Carroll, D. C. ^[2]; Yuan, X. H. ^[3]; Borghesi, M. ^[4]; Neely, D. ^[5]

---

1. Centro de Laseres Pulsados (CLPU), Parque Cientifico, Calle del Adaja s/n. 37185 Villamayor, Salamanca (Spain)
2. Central Laser Facility, STFC Rutherford Appleton Laboratory, Oxfordshire OX11 0QX (United Kingdom)
3. Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)
4. Centre for Plasma Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom)
5. SUPA Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

Multiple ion acceleration mechanisms can occur when an ultrathin foil is irradiated with an intense laser pulse, with the dominant mechanism changing over the course of the interaction. Measurement of the spatial-intensity distribution of the beam of energetic protons is used to investigate the transition from radiation pressure acceleration to transparency-driven processes. It is shown numerically that radiation pressure drives an increased expansion of the target ions within the spatial extent of the laser focal spot, which induces a radial deflection of relatively low energy sheath-accelerated protons to form an annular distribution. Through variation of the target foil thickness, the opening angle of the ring is shown to be correlated to the point in time transparency occurs during the interaction and is maximized when it occurs at the peak of the laser intensity profile. Corresponding experimental measurements of the ring size variation with target thickness exhibit the same trends and provide insight into the intra-pulse laser-plasma evolution.

• OSTI ID: 22598941
• Journal Information: Physics of Plasmas, Vol. 23, Issue 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ACCELERATION
BEAMS
DISTRIBUTION
EXPANSION
FOILS
INTERACTIONS
IONS
IRRADIATION
LASERS
OPACITY
PEAKS
PLASMA
PROTONS
PULSES
RADIATION PRESSURE
THICKNESS
VARIATIONS