Non double layer regime a new laser driven ion acceleration mechanism toward tev
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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 )

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Non double layer regime a new laser driven ion acceleration mechanism toward tev
Non Double-Layer Regime: a new laser driven ion acceleration mechanism toward TeV


Outline
outline acceleration mechanism toward TeV

  • significance、implications、goals for high energetic ion beams

  • one-stage acceleration:target normal sheath acceleration (TNSA)、phase-stable acceleration or radiation pressure acceleration(RPA)

  • multi-stage acceleration for TeV proton beam:

    non double layer regime

  • Tens TeV or even higher energetic heavy ion beam


1 motivation and current situation of laser plasma ion acceleration
1.Motivation and current situation of laser-plasma ion acceleration

The produced high energetic ion by target normal sheath acceleration( TNSA)experimentally:

  • energy gain:67MeV for proton and 500MeV for Carbon ion.

  • acceleration field strength: 100 GV/m --10000 GV/m

  • energy spread: 20%

  • good repetitiveness

    applications:ion cancer therapy、fast ignition of

    thermonuclear fusion、high energy physics and astrophysics

    goals :mono-energetic、collimated、higher energy、higher transfer efficiency


2 one stage acceleration

TNSA acceleration

2.One stage acceleration

Laser

2.1(a) TNSA

Thick solid target

Typical values:


2 one stage acceleration1

v acceleration

Thin solid target

2.One stage acceleration

2.2 circularly polarized laser-thin target interaction for ion acceleration ------phase stable acceleration or radiation pressure acceleration

From an immobile sheath to a moving sheath/double layer


2 one stage acceleration2
2.One stage acceleration acceleration

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,

green:proton

blue:electron

matching condition:


2 one stage acceleration3
2.One stage acceleration acceleration

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))


2 one stage acceleration4

Phase space (x~p accelerationx)

A

B

A

B

2. One stage acceleration

X. Yan et al., PRL 100, 135003 (2008) ; Bin.Qiao et al,PRL 102,145002(2009);

X. Yan et al., PRL 103, 135001 (2009); M. Chen et al., PRL 103, 024801(2009);


Linearly polarized laser pulse thick solid target 2002
Linearly polarized laser pulse + thick solid target (2002) acceleration

TNSA regime

length: ld

energy:67MeV

Circularly polarized laser pulse + thin solid target (2008)

Phase stable regime:

length: tens mm

energy: GeV

Circularly polarized laser pulse + combination target

Non-double-layer regime

length:cm

energy:TeV

?????


3 multi stage acceleration for proton beam non double layer regime
3.multi-stage acceleration for proton beam: non double layer regime

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.

matching condition:


Wakefield structure electron and proton density

Simulation parameters regime :

laser pusle:

a0=250;foil: 20nc,D=0.5mm;gas length:12000mm,0.01nc

Wakefield structure、electron and proton density

double layer:

Non-double layer :


Wakefield structure phase space and energy distribution of proton beam
Wakefield structure, phase space and energy distribution of proton beam

t=5000Tl

t=12000Tl

Maximum relativistic factor Gamma=580,Wmax >0.5TeV, 8 times higher than that in the double-layer regime


Dynamical process in the non double layer regime versus background gas density
Dynamical process in the non-double layer regime versus background gas density

distance between the electron and proton layer

maximum electrostatic field

Maximum energy scaling :

maximum energy

Dephasing length

Minimum gas density:


4 heavy ion toward tens tev
4.Heavy ion toward tens TeV background 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:


Simulation results for carbon ion beams: the same laser and plasma parameters as given for proton beam

t= 0.5Tl

t= 0.6Tl

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.


Wakefield structure, electron density, carbon ion density, laser pulse

t=5000Tl

t=15000Tl

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%


Heavy ion information laser pulse

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


THANK YOU! laser pulse


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