A hydrodynamic stability study of igniting direct-drive ICF targets at hundreds of kJs of laser energy

After the recent achievement of ignition at the Nation Ignition Facility (NIF), there is now considerable interest in building a direct-drive laser facility that leverages next-generation laser technology to perform high quality implosions at a considerable rep-rate. Present direct-driver experiments are degraded by laser-plasma instabilities (LPI) which act to scatter energy away from the plasma and reduce ablation pressure - a critical parameter for achieving high-performance implosions [1]. Mitigating LPI is therefore a key design requirement for future laser drivers. Recent LPI modeling results [2,3] indicate that increasing the laser bandwidth significantly raises LPI thresholds. When combined with focal-spot zooming, this approach enables ablation pressures exceeding 200 Mbar at an overlapped intensity of 1x10¹⁵ W/cm². Such performance opens the possibility of achieving ignition under direct-drive conditions with moderate laser energies (250 kJ). We present a series of multidimensional simulations that investigate the stability of these target designs in the presence of both laser and target nonuniformities.