Abstract
StarDriver was recently proposed as a highly flexible laser driver for inertial confinement fusion and high energy density physics. It envisions a laser drive consisting of very many beams at an aperture and energy where the optical technology is well-developed, used in concert to create a large scale laser driver system. In this paper we describe a StarDriver–class laser with 5120 physical beamlets disposed about the target chamber in 80 evenly spaced ports, each port containing 64 beamlets, each beamlet having about ~1.5 THz of 2D SSD bandwidth and suitable phase plates, an aperture of ~65 mm, an energy of 80 J, and frequency-converted to ~351 nm. StarDriver has many beamlets at an aperture where optical technology is well-developed, and each beamlet has energy ~100 J in a several times diffraction limited beam. The ensemble of beamlets has frequency bandwidth 2%-10%, thereby providing significant control of both hydrodynamic and laser-plasma instabilities The drive at the target is ~400 kJ, has a well-behaved low L-mode spectrum, and smooth’s very rapidly, reaching an asymptotic smoothness of <1% in less than 1 ns. We also review recent results showing that the 2ωpe instability can be significantly reduced by 20 THz bandwidth.
Highlights
To achieve the plasma conditions required for Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP) drivers that effectively compress energy in space and time and whose energy can be effectively delivered to an appropriate target are required
It is expected over the decade that experiments on NIF will explore the physics of a variety of target concepts with MJ-sized plasmas representative of attractive ”high gain” target configurations, further develop quantitative predictive simulation tools and hopefully demonstrate fusion ignition and modest fusion gain (G>10)
We have simulated [9] the on-target time-dependent intensity profile of a StarDriver-class Inertial Fusion Energy (IFE) driver with 5120 physical beamlets disposed about the target chamber in 80 evenly spaced ports, each port containing 64 beamlets, each beamlet having about ~1.5 THz of 2D SSD bandwidth and suitable phase plates, an aperture of ~65 mm, an energy of 80 J, and frequency-converted to ~351 nm
Summary
To achieve the plasma conditions required for Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP) drivers that effectively compress energy in space and time and whose energy can be effectively delivered to an appropriate target are required. Namely Inertial Fusion Energy (IFE), lasers with average power of nominally 10-20 MW at repetition rates of ~10 Hz with driver efficiencies >10% are required It is expected over the decade that experiments on NIF will explore the physics of a variety of target concepts with MJ-sized plasmas representative of attractive ”high gain” target configurations, further develop quantitative predictive simulation tools and hopefully demonstrate fusion ignition and modest fusion gain (G>10). With less than 10,000 beamlets, each with 2D SSD, spanning 2% bandwidth, the laser drive on target is asymptotically less than 1% and is reached in less than 1 ns This performance is a very significant improvement over legacy ICF laser drivers and will ease, significantly, the constraints on target concepts arising from hydrodynamic instabilities. A bandwidth of 20 THz would significantly reduce the instability and a bandwidth OD 35 THz migh suppress it completely
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