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Defense Speak Interpreted: Weapons—Electrical Power vs. Energetics

I have wondered for years if electrical power could compete with gunpowder in defense weapons systems. Think of the advantages: Nothing in your vehicle would explode if enemy gunfire hit you, and there would be no armor to protect your powder magazine. The Accurate Energetic Systems, LLC (AES) explosives facility in Humphreys County, Tennessee, explosives plant that blew up on Oct. 10, was not making ammunition, but it reminded us of the danger of “energetics.” This column explores the aspects of hitting and destroying targets. A future column will explore propellants.

What are energetics? According to Gemini AI: "Energetics" refers to materials and devices that rapidly release large amounts of stored chemical energy, with explosives being a major category, alongside propellants and pyrotechnics. These materials are composed of fuel and oxidizer components designed for fast, high-energy reactions, and are critical for military, industrial, and specialized civilian applications like propulsion, warheads, and aircrew escape systems. 

But what about lithium batteries? We are warned that they can “blow up” that is, decompose so rapidly they resemble explosives. They have stored chemical energy. Does that make them energetics? If batteries can be energetics, what about more common energy storage components: capacitors? 

Fortunately, there is a common metric between traditional energetics and electric power: the unit of energy, the joule. In mechanical/explosive terms, a joule is equal to the amount of work done when the force of one newton displaces a body through a distance of one meter toward that force.

A joule is also the energy that dissipates as heat when there is an electrical current of one ampere through a resistance of one ohm for one second. In electrical terms, a joule is the work required to produce one watt of power for one second, or one watt-second (Ws). Let’s try to relate kinetic energy to electrical (laser) energy in drone warfare in the battles in Ukraine. We wonder about blowing up incoming dangerous drones by giving them a pulse of laser (electromagnetic) energy. 

I thought about this as I pointed a handheld green laser at a blank presentation screen. How much power do we need for a laser to defeat incoming small drone weapons? What about the electrical energy driving anti-drone weapons mounted on ships and land vehicles? Are we on the edge of “disintegrator” weapons of the Buck Rogers days, almost 100 years ago? 

A Sept. 18 Reuters article posted the headline: “Israeli Anti-missile Laser System 'Iron Beam' Ready for Military Use This Year.” Electronic/electric weapons have several advantages:

• Ready to fire at the touch of a switch.
• No ammunition. Read that as no energetics.
• Hopefully, continuous delivery of destructive power, or at least a short reloading time for pulses
• Hopefully, being selective in targeting will minimize collateral damage.

We can start our comparison based on energy density—the amount of energy stored in a system, substance, or region of space, measured either per unit of volume (like J/m3) or per unit of mass (like Wh/kg). The amount of energy stored in a specific amount of space. This is often called volumetric energy density. The amount of energy stored in a specific amount of mass is known as gravimetric energy density. 

Materials with higher energy density can store more energy in a smaller or lighter package, which is crucial in applications where space and weight are limited, such as in portable electronics, electric vehicles, and aircraft. A higher energy density means it’s possible to store more energy, making devices more efficient and practical. For example, higher energy density batteries allow for longer driving ranges in electric cars without increasing battery size or weight.  But how much energy does it take to destroy an enemy drone? It depends. Factors such as weight, armor, and speed cause problems with calculations, but let’s limit the discussion today to Group One drones up to 20 pounds. 

Google Gemini reports: "The energy required to destroy a Class 1 drone depends on the method used, but a hard kill from a directed energy weapon (DEW) requires a fluence on the order of 10,000 J/cm2 concentrated on the target. For lasers, the energy is delivered as a beam that can cause physical damage by burning components, while high-power microwave (HPM) devices use electromagnetic energy to destroy a drone's hardware. The exact energy is highly variable and depends on factors like the drone's construction, the weapon's capabilities, and environmental conditions. 

Factors influencing energy requirements:

Concentration of energy: Energy must be concentrated in a small area and a short amount of time to be effective, preventing heat from dissipating.

Energy delivery method: Different weapons deliver energy differently.

• Lasers: Deliver a concentrated beam of light that can burn or damage components.
• High-Power Microwaves (HPM): Emit intense beams of high-power electromagnetic energy that can destroy a drone's hardware by overwhelming its systems.

Distance and atmospheric conditions: The energy delivered decreases with distance due to factors like absorption, scattering, and divergence. Adverse weather can also affect the performance of lasers.

Drone's construction: A drone's materials and construction will affect how much energy it takes to damage it. For example, a drone with components hardened against jamming may require more energy to disable or destroy."

I won’t get into the construction of a laser weapon that can concentrate the beam into a 1-square-centimeter area, but 10,000 watts, or 10 kilowatts, is significantly more than my 5-milliwatt green laser pointer—2 million times greater. That converts to roughly 13.5 horsepower to kill a drone up to 20 pounds. That is the approximate power output of my riding lawn mower.

Now that we have covered the small, individually guided drones used in Ukraine, what about laser weapons for incoming missiles? In the Reuters article about Israel’s Iron Beam laser anti-missile interception system: imagine the horsepower needed to drive a missile-killing laser, not just shoot down a drone? To develop laser-based killer weapons, Google Gemini advises: 

To optimize energy conversion in large anti-drone lasers, consider the following steps:

1. Utilize high-efficiency laser diodes to maximize output.
2. Implement advanced cooling systems to maintain optimal operating temperatures.
3. Integrate energy storage solutions for consistent power supply.
4. Optimize beam focusing techniques to enhance targeting accuracy.
5. Employ real-time monitoring systems for performance adjustments.
6. Explore renewable energy sources to reduce operational costs.

Electric weapons are coming, but they are not the hand-held disintegrator guns that Buck Rogers used a century ago. My upcoming column will explore the concept of railgun propulsion of artillery shells from ships or land-based weapons.

Denny Fritz was a 20-year direct employee of MacDermid Inc. and retired after 12 years as a senior engineer supporting the Naval Surface Warfare Center in Crane, Indiana.