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Non Double-Layer Regime: a new laser driven ion acceleration mechanism toward TeV. outline. significance 、 implications 、 goals for high energetic ion beams one-stage acceleration ： target normal sheath acceleration (TNSA) 、 phase-stable acceleration or radiation pressure acceleration(RPA )
non double layer regime
The produced high energetic ion by target normal sheath acceleration( TNSA）experimentally：
applications：ion cancer therapy、fast ignition of
thermonuclear fusion、high energy physics and astrophysics
goals ：mono-energetic、collimated、higher energy、higher transfer efficiency
2.2 circularly polarized laser-thin target interaction for ion acceleration ------phase stable acceleration or radiation pressure acceleration
(a) The light pressure balances the electrostatic pressure to form
double layer (electron and ion layer) structure,
b.The ion dynamical motion obeys：
scaling law : p>>1， dp/dt ∝ (1/p2) , p ∝ t1/3, x1/3
（T. Esirkepov et al., PRL92,175003 (2004)）
Circularly polarized laser pulse + thin solid target (2008)
Phase stable regime:
length: tens mm
Circularly polarized laser pulse + combination target
The light pressure exerted on the electron layer is larger than the electrostatic pressure. The electron layer is pushed out by the ponderomotive force before double-layer is formed.
Maximum relativistic factor Gamma=580，Wmax >0.5TeV, 8 times higher than that in the double-layer regime
distance between the electron and proton layer
maximum electrostatic field
Maximum energy scaling ：
Minimum gas density：
4.1dynamical equation in describing the acceleration process of heavy ion
Assuming the same acceleration length for both proton and heavy ion
Defining the dephasing length ratio between heavy ion and proton：
the maximum energy of heavy ion reads:
In the non-double layer regime: the electron layer runs faster than the carbon ion layer . The double-layer structure can’t be formed in the laser-foil stage.
The acceleration process is terminated at t=15000Tl ,meanwhile the laser pulse is completely absorbed, suggesting that the dephasing length is equal to pump depletion length.
The inset in Fig.(d) indicating: the energy transfer efficiency converted to carbon ion is greater than 30%
The longitudinal phase space and energy spectrum of the trapped carbon ion at t=15000Tl
Maximum energy of carbon ion versus time in unit of laser cycles (a); maximum energy for different ion with charge number Z (b).
C6+ : 3.2TeV
Cu29+ : 16TeV
Au50+ : 25TeV