For nearly a century, scientists have dreamed of harnessing the power of the sun and stars to generate electricity. Fusion combines the atomic nuclei of two isotopes of hydrogen: deuterium (one proton and one neutron) and tritium (one proton and two neutrons). The reaction creates one helium atom (two protons and two neutrons) plus one free neutron plus energy. Lots of energy.
Nuclear fusion is incredibly efficient. A 1000 mega Watt coal-fired power plant requires 3 million tons of coal per year, but a fusion plant will only need 550 pounds of fuel per year, half of it deuterium, half of it tritium.
Deuterium is naturally abundant. About one out of every 5,000 hydrogen atoms in seawater is deuterium. This means our oceans contain many tons of this isotope. When fusion power becomes a reality, just one gallon of seawater could produce as much energy as 300 gallons of gasoline.
Tritium, on the other hand, is quite rare. The atmosphere has only trace amounts, formed by the interaction of its gases with cosmic rays. But it can be produced at commercial scale by neutron bombardment of metallic lithium or lithium-bearing ceramic beads in special nuclear breeder reactors. Future fusion reactors may also produce tritium within a helium-cooled ceramic pebble bed called a breeder blanket.
Deuterium is one of two stable isotopes of hydrogen and is therefore not radioactive. Tritium is unstable but emits only weak beta radiation (an electron). It has a short half-life of about twelve and one-third years. While beta radiation from tritium decay won't even penetrate human skin, it can be injurious if breathed in or ingested. Fortunately, a single exposure only remains within the body for about a week, flushed out during the body's normal water cycling processes.
For fusion to occur deuterium and tritium must be heated to a plasma (elections become unbound to any atomic nuclei), under intense pressure. For example, the temperature at the very center of the Sun is about 27 million degrees Fahrenheit, at an estimated 265 billion atmospheres (3.84 trillion psi).
Fusion reactors are rated by a factor called fusion energy gain (Q). Q is the ratio of the energy produced divided by the thermal power injected to superheat the plasma and initiate the reaction. For a reaction to be self-sustaining, the reactor must have a fusion energy gain factor of 1 or greater.
Two successful fusion reactor designs Tokamak. In 1950 soviet scientists Andrei Sakharov and Igor Tamm proposed using a torus(donut-shaped) magnetic field to constrain deuterium-tritium plasma. The magnetic field is partially externally generated and partially generated by inducing an electric current in the plasma itself. Tokamaks confine their fuel at low pressure (around 1 millionth of an atmosphere) but high temperatures(150 million degrees Celsius) and attempt to keep those conditions stable for ever-increasing times on the order of seconds to minutes. In 1997 the Joint European Torus (JET) tokamak, succeeded in generating a Q of 0.67.
The most advanced tokamak facility, ITER, is under construction in southern France. ITER is a thirty-five-country collaborative nuclear fusion experiment. It is expected to be the first tokamak reactor to achieve a net gain, where the heat of fusion is sufficient to heat incoming plasma, maintaining a sustained reaction.
Inertial Confinement. In the 1970s, scientists began experimenting with laser beams to compress and heat the hydrogen isotopes to the point of fusion. Today, the leading inertial confinement project is the National Ignition Facility (NIF) at Lawrence Livermore Laboratory. NIF precisely guides, amplifies, reflects, and focuses 192 powerful lasers into a target about the size of a pencil eraser in a few billionths of a second. It generates temperatures in the target of more than 180 million degrees F and pressures of more than 100 billion Earth atmospheres. In August of 2021, the National Ignition Facility set the record for Q at 0.70. Inertial confinement reactors are envisioned to produce power in pulses, rather than a steady reaction like tokamak reactors.
Can a fusion reactor explode or melt down? In a word, no. A few grams of fuel is sufficient to produce the heat to maintain fusion and generate electricity in a tokamak reactor. A working inertial confinement reactor may require fuel pellets as small as one gram. Whenever plasma containment is lost, it results in both a loss of temperature and pressure. The reaction simply winks out, like a thermonuclear candle flame in the wind.
Nuclear reactors utilize hundreds of pounds of highly radioactive uranium-235 or plutonium. The fuel must be constantly cooled and/or damped to prevent a runaway reaction. Once a meltdown occurs, and containment is lost, radioactive material can spread across the globe. The half-life of U-235 is about 700 million years. Once the genii is out of the bottle, it doesn't go away.
Fuel for fusion reactors is either nonradioactive(deuterium) or weakly radioactive (tritium) with a half-life of a dozen years. A fusion reaction is highly controllable. It can be stopped instantly, long before any sort of reactor vessel breach is even possible. If a vessel is ever breached under conditions of war or sabotage, the quantity of tritium is so small, it would be virtually unmeasurable outside the reactor.
Will fusion reactors power bases on Mars? Not in the foreseeable future. Fusion reactors have yet to achieve break-even ignition, let alone a self-sustaining reaction. I expect this to be achieved within the next ten years or so. Then reactors will have to be fine-tuned to be able to be economically viable. The power produced and sold must exceed the cost of development and construction. Barring some unanticipated technological breakthrough, this won't occur until around 2050.
Then there is the matter of size. NIF is as big as a sports stadium. The ITER campus is the size of 60 soccer fields! Of the two technologies, I think inertial confinement is most amenable to miniaturization. But to be a candidate for transport to Mars, an inertial confinement plant would have to be as a small as a shipping container.
And there is the issue of providing the power
for ignition. When it comes to fusion, it takes energy to make energy. What's not known is the power required to produce the roughly 2 MW needed for ignition. A small base on Mars will only need four or five 10 kW generators. Given the extreme brevity of the laser pulses required to ignite a single fusion power plant, It's possible a supplemental power source wouldn't be needed but it's a complication that could only add to the volume and mass required to provide fusion energy on Mars.
So, I don't foresee fusion power in use on Mars until well after 2050. But who knows? If Dr. Emmett Brown can come up with a Mr. Fusion model that runs on banana peels, maybe there's a chance.
For Further Readinghttps://en.wikipedia.org/wiki/Nuclear_fusionhttps://www.iaea.org/topics/energy/fusion/backgroundhttps://en.wikipedia.org/wiki/Tritiumhttps://en.wikipedia.org/wiki/Deuteriumhttps://en.wikipedia.org/wiki/Tokamakhttps://en.wikipedia.org/wiki/Stellaratorhttps://scitechdaily.com/fusion-breakthrough-once-thought-impossible-brings-energy-device-closer-to-realization/https://www.sciencedaily.com/releases/2021/08/210831095614.htmhttps://scitechdaily.com/fusion-breakthrough-at-the-brink-of-fusion-ignition-at-national-ignition-facility/ 
