Limitation on prepulse level for cone-guided fast-ignition inertial confinement fusion

Area of Science:

• Plasma Physics
• Fusion Energy
• Laser-Plasma Interactions

Background:

• Fast-ignition (FI) inertial confinement fusion requires efficient laser energy transfer to fuel via multi-MeV electrons.
• Laser prepulses create preplasma, significantly impacting ultraintense laser-plasma interactions and hot electron generation in hollow cone targets.

Purpose of the Study:

• To investigate the influence of laser prepulses on preplasma formation and subsequent energy deposition in FI targets.
• To measure the energy deposition zone of the main laser pulse by imaging K-alpha radiation.
• To understand the underlying mechanisms of energy deposition and hot electron generation.

Main Methods:

• Induction of a prepulse and consequent preplasma in copper cone targets.
• Measurement of the energy deposition zone using K-alpha radiation imaging.
• Radiation hydrodynamics simulation of preplasma and particle-in-cell modeling of main pulse interaction.

Main Results:

• Preplasma formation was induced and characterized.
• K-alpha radiation imaging provided measurements of the energy deposition zone.
• Simulations of preplasma hydrodynamics and main pulse interaction showed good agreement with experimental data.
• A 100 mJ prepulse was demonstrated to eliminate the forward-going component of approximately 2-4 MeV electrons.

Conclusions:

• Laser prepulses significantly alter laser-plasma interactions in FI targets.
• The study provides insights into energy deposition mechanisms and electron distributions.
• Controlling preplasma with prepulses can optimize energy transfer for fast-ignition fusion.