This concept models a high-efficiency, high-temperature laser system based on ytterbium-doped molten FLiBe (Yb:FliBe), operating at a wavelength of 1050 nm. Ytterbium is a well-established laser dopant known for its:
Simple electronic structure
Low quantum defect
High efficiency and energy storage
Long upper-state lifetime (~4× that of neodymium)
Its properties make it ideal for pulsed, high-power lasers operating in extreme environments, such as inside the BS-Fusion reactor.
This approach avoids the inefficient UV-x-ray conversion step used by the National Ignition Facility (NIF), which suffers a ~5% wall-plug-to-target efficiency when converting 1053 nm light to x-rays.
Comparison with Other Fusion Heating Methods
Ohmic Heating (e.g., in Tokamaks):
Efficiency: ~100% (initial phase only)
Limitations: Ineffective beyond a few keV; requires auxiliary heating
Radio Frequency (RF) Heating:
Grid-to-plasma efficiency: ~50%
Losses: Occur in power generation, waveguides, antennas
Neutral Beam Injection (NBI):
Efficiency: Often <30%
Loss Sources: Ion acceleration, neutralization, shine-through
ITER projection: ~26% net efficiency, even with negative-ion beams
Conclusion
A heat-capacity laser based on molten Yb:FliBe provides a direct and efficient path to deliver high-energy, long-wavelength laser light to the fusion fuel. With minimal frequency shifting, strong heat recovery assumptions, and the elimination of intermediate conversions, overall efficiencies of 38–53% appear feasible, potentially outperforming traditional magnetic confinement heating methods.
Rare-earth ions (in molten halide salts) are known to luminesce with measurable absorption/emission features, so a Yb:FLiBe laser is not impossible, but to claim it would operate efficiently at 750 K is doubious.
A neodymium (Nd)-based laser is more likely to maintain a 4-level system at high temperatures (>750 K) than a ytterbium (Yb)-based laser due to fundamental differences in their energy level structures and thermal sensitivities:
Key Differences in Energy Level Structures
Nd³⁺ (Neodymium)
4-Level System: Nd lasers typically operate with a 4-level scheme, where the lower laser level is well above the ground state.
Thermal Advantage: At high temperatures, the population of the ground state remains low enough that reabsorption from the lower laser level is minimal.
Robustness: The energy gap between the laser transition and the ground state is large enough to suppress thermal population of the lower level, preserving efficient lasing.
Yb³⁺ (Ytterbium)
Quasi-3-Level System: Yb lasers often operate with a quasi-3-level scheme, where the lower laser level is the ground state or very close to it.
Thermal Sensitivity: At elevated temperatures, thermal excitation populates the ground-state manifold significantly, leading to:
Hot-band absorption: Increased reabsorption of the emitted laser photons.
Multiphonon quenching: Non-radiative decay of the upper laser level due to coupling with lattice vibrations (phonons), especially in molten salt hosts.
High-Temperature Behavior
Nd-Based Lasers: More resilient to thermal effects because the lower laser level remains depopulated even at high temperatures, preserving the 4-level dynamics.
Yb-Based Lasers: Efficiency drops at high temperatures due to:
Increased reabsorption from thermally populated ground-state levels.
Reduced upper-state lifetime from multiphonon quenching
Summary
Feature
Nd³⁺ Laser
Yb³⁺ Laser
Laser Scheme
True 4-level
Quasi-3-level
Lower Level Population
Low at high T
High at high T
Reabsorption Risk
Minimal
Significant
Multiphonon Quenching
Less severe
More severe
High-T Efficiency
More stable
Decreases sharply
So in molten salt or other high-temperature hosts, Nd-based lasers retain their 4-level behavior and efficiency better than Yb-based lasers, which suffer from thermal reabsorption and quenching effects
These might work if the upper-state lifetime can be increased. For example, it takes 125 microseconds to deliver 2 MJ (optical) using 20,000 of these 800 kW laser-diode array modules.
Leonardo manufactures 1.8 MW (optical) laser diode modules with 52% electric-to-optical conversion efficiency. These modules support 500-microsecond pulses and a 50% duty cycle.
In theory, deploying 100,000 of these modules could deliver pulses of 20 MJ—roughly 10× the energy delivered to NIF targets—in 111 microsecond bursts. However, if each module costs more than $10,000, a single BSF power plant would require over a billion dollars’ worth of laser diode hardware. That level of expenditure is totally impractical.
BSF is a joke—it assumes a rediculous, fatally flawed economic model! Consider the basic fact, which BSF violates: For an economically viable power plant, the cost of construction must be recouped before the plant closes for decommisioning.
Let’s do the math.
BSF Construction Price Tag
Laser diode module: $10,000
Number of modules: 100,000
Subtotal: $1 Billion
If lasers represent half the plant cost: Total = $2 billion
Yearly Energy Production
Target rate: 1 every 15 seconds
Energy per target: 330 MJ
Thermal-to-electric conversion efficiency: 25%
Shots per year: ~32 million
Total energy/year = 1.8*10^14 J
So, it would take a miracle (a BSF power plant would need to run continuously without profit for more than three hundred years) just to break even.
Conclusion: BSF power plants cannot generate profit—they are billion-dollar crypts, entombed beneath layers of molten salt optimism. Anyone foolish enough to begin construction of one should be stopped ASAP. A granite slab should be errected at the site, engraved to display through the centuries: ‘Here lies ROI—sacrificed for optics.’
Ferengi worship profit—it’s their guiding principle, their moral compass, and their cultural identity. Their philosophy is codified in the infamous Rules of Acquisition, a sprawling set of 285 business maxims that govern every transaction and social interaction.
Highest is Rule #1: “Once you have their money, you never give it back.”
In Ferengi economics, if the money borrowed to build a BSF power plant doesn’t need to be repaid for 307 years, it would be a wise acquisition.
That conclusion is as premature as a toddler modeling thermohydraulics in crayon.
While your math easily penitrates the target you chose, its scope is narrower than a collimated neutron beam. You only modeled a single scenario. BSF’s parameter space is vast, uncharted, and riddled with knobs no one’s dared to twist. To draw a general conclusion at such an early and unexplored stage is unjustified.
The way you portrayed BSF, as a necropolis—where capital goes to die, was humorous. However, your analysis was based on several assumptions detrimental to plant performance. Obviously, if the assumptions are bad enough, the payback timeline can be stretched into geological epochs. Instead of focusing on examples with poor efficiency, let’s focus on how to improve the assumptions.
Red’s Assumptions
1. Laser diode modules: $10,000
2. Number of modules: 100,000
3. Target rate: 1 every 15 seconds
4. Energy per target: 330 MJ
5. Thermal-to-electric conversion efficiency: 25%
#1. Future Cost Reduction: Moore’s Law & Learning Curve
The good news is that laser diode costs are expected to plummet with large-scale production and technological improvements – much like semiconductors and solar panels have in the past. Two conceptual models can be used to project future prices under high-volume manufacturing:
Moore’s Law Analogy: In the microchip industry, Moore’s Law observed that the number of components (transistors) on a chip doubled roughly every 2 years with minimal cost increase. In practice, this meant cost per function halved with each doubling of technology – an exponential improvement. If a similar trend held for high-power laser diodes, the cost per watt could halve with each doubling of cumulative production. This is an extremely rapid learning rate.
20% Reduction per Doubling (Learning Curve): Many energy technologies follow a more modest learning curve. Swanson’s Law for solar PV is a classic example – solar module prices tend to fall ~20% with each doubling of cumulative output. This corresponds to an “80% learning rate.” Every doubling of production cuts cost to 80% of its previous value. For instance, 20 doublings (~1048576×volume) would reduce cost to about (0.8)^{20}≈0.012 (approximately 1.2% of the original cost). In practical terms, if a module costs $100k in early low-volume production, the price would fall to about $1,200.
This analysis spanned a range from very aggressive improvement (Moore-like) to conservative improvement (20% learning rate). Real-world outcomes could fall in between. Notably, semiconductor lasers are semiconductors, so with large demand, they could start behaving more like mass-produced microchips or LEDs in terms of cost curve. Historical data shows laser diode prices have fallen dramatically as power and efficiency improved. In 2015, state-of-the-art pump diodes for high-energy lasers cost on the order of $5/W; a few years ago this had dropped below $1/W, and roadmaps aim for a few cents per watt in the coming decade. This trend results from improvements in diode efficiency (reducing waste heat hardware), higher output per chip, and automated manufacturing.
#2. Laser Power (+) Shared Amongst Multi-chambers
The drivers are the most expensive components in inertial confinement fusion (ICF) power plants. In a multi-chamber ICF plant, several blast chambers can share one driver system through time-multiplexing. If a laser is used, the driver only needs to pump for a few microseconds, while clearing the chamber between shots takes several seconds. Thus, the laser modules spend most of their potential duty cycle idle in a single-chamber setup. By rotating pulses between many chambers, the same diode array can be kept busy nearly continuously, increasing utilization without exceeding thermal or duty-cycle limits. This means the high capital cost of the driver is spread over many more fusion events per second, lowering the effective cost of the laser per unit of power produced.
The same principle applies to turbines and power conversion systems. When multiple chambers fire in sequence, the combined energy flow into the heat exchangers and turbines becomes smoother and more continuous, allowing the use of larger, shared infrastructure instead of duplicating equipment for each chamber. Large turbines are cheaper per watt and more efficient than many smaller ones, and the balance-of-plant (cooling, piping, generators, grid connection) can also be consolidated. Together, these shared components distribute fixed costs across greater output, so the gigawatts of electricity delivered per dollar invested rise substantially, reducing the plant’s overall cost-per-watt of electricity.
#3. Faster Target Delivery
In Red’s senario, one 330 MJ target gets ignited every 15 seconds. When these targets are fused, their heat energy gets deposited near the ignition site, in coolant at the center of the blast chamber. This heat needs to be exchanged (removed from the blast chamber) by circulating coolant through it. The per shot volume of coolant that needs to be exchanged (inlet → outlet) can be calculated:
V_{\text{per-shot}}=\frac{E}{\Delta T \rho C_p} = 0.2 m^3
where:
energy supplied, E = 3.3E8 J
temperature swing, \Delta T = 1100-750 => 350 K
density, \rho = 2000 kg/m^3
specific heat, C_p = 2414 J/kg\cdot K
So, under Red’s assumptions, 0.2 m^3 of coolant would be flowing through the inlet/outlet every 15 seconds (0.8 m^3/\text{minute}). This is two orders of magnitute slower than typical fission reactors, which have volumetric flow rates ranging from 57 to 95 cubic meters per minute.
#4. Higher Yield Targets
#5. Increased Carnot Efficiency
The theoretical maximum efficiency of any heat engine is given by:
Key Differences in Energy Level Structures
High-Temperature Behavior
Summary