Theoretical fusion and antimatter systems can allow developers to create crafts for travel around the solar system and beyond.

   Theoretical fusion and antimatter systems can allow developers to create crafts for travel around the solar system and beyond. 

There are many concepts about the interplanetary and interstellar spacecraft. The most promising systems are pulsed plasma fusion reactors and positron reactors. But stars are a little bit too far for those systems that allow them to travel around the solar system. 

"Florian Neukart, an Assistant Professor at the Leiden Institute, has proposed the Magnetic Fusion Plasma Drive (MFPD) as a novel space propulsion method. This concept combines fusion propulsion, ionic propulsion, and more, promising high energy density and fuel efficiency". (ScitechDaily.com/Interstellar Travel: Magnetic Fusion Plasma Engines Could Carry Us Across the Solar System and Beyond)

Let's start with the most futuristic model of those engines. 

1) Zero-point energy.

The Zero-point energy means the minimum energy level in the system. Energy always travels to the lower energy point. And if we would create the quantum system like a metal cube that is at the absolute zero kelvin temperature. Then we can put a high-temperature object behind that zero-energy particle. Energy starts to travel through that zero-energy object and pushes the craft forward. The engine system can inject zero-energy particles into the rocket's exhaust tube. When hot exhaust gas impacts those particles it expands them.  Causing expansion in those particles which should increase thrust and decrease temperature in exhaust gases. 

The pulsed plasma engine can connect with a point engine system. In that system is the extreme cold point in the pike. The fusion material will drive to that cold point and the laser ignites fusion. The idea of that liquid helium-based system is to stabilize the fuel before ignition. When the system impacts energy to the shell of that fuel ball the impact wave travels in the fusion material and reflects from there. The system can press that fuel from both sides. And that creates the fusion reaction. 

"What will it take before human beings can travel to the nearest star system within their own lifetimes? Credit: Shigemi Numazawa/ Project Daedalus" ((ScitechDaily.com/Interstellar Travel: Magnetic Fusion Plasma Engines Could Carry Us Across the Solar System and Beyond)

2a) The Magnetic Fusion plasma drive. (MFPD)

The fusion reactor creates high-energy plasma in the chamber. Then the particle accelerators will send it backward. The system can use miniaturized particle accelerators. That can shoot anions and ions together. The engine drives that plasma backward. The speed that this system can give is enormous. 

2b) Pulsed plasma fusion. 

In pulsed plasma fusion, the reactor creates plasma bubbles. Then the magnetic field presses that plasma together. And the laser system will ignite fusion in that system. The simplest model is the machine gun that shoots plutonium-lithium pellets to laser ray. 

Sometimes pulsed plasma fusion is called a "linear fusion" system. In that model, two- or more particle accelerator lines drive plasma or anions and ions to the same point. Then the laser ray will ignite fusion in that plasma. The system can burn fusion behind the craft. And the plate behind it takes energy impacts into it. 

There was a theoretical saucer-shaped concept craft there were particle accelerators below the craft. Those particle accelerators shot anions and ions into the middle of it. And then the laser system ignites fusion in those impacting particles. 

2c) Tokamak type fusion system. 

The tokamak reactor can also act as a fusion engine. In that case, the craft has this reactor in it. There is a hatch in that donut-shaped reactor that allows to aim of particles in the right direction. And that causes thrust for the craft. 

The tokamak or torus fusion reactors can be like belts around the O'Neill cylinders. That thing makes those systems act like Tipler-cylinder or Tipler time machines. The fast-orbiting plasma will make time dilation in those systems. 

In some models, the tokamak-type fusion engine is installed in a saucer-shaped craft. That reactor would be the outer edge of the saucer. The accelerator system transports particles in the middle of that saucer, where they create fusion or annihilation. 

The tokamak reactor could cause time dilation in the spacecraft, which makes it the Tipler cylinder. And that allows the crew to make interstellar travels. But people who send that saucer to journey will never meet those people again, because time dilation happens only in the craft. 

The tokamak system can connect with a pulsed plasma engine that is middle of the craft. The engine pulls ions through it. And then lasers will ignite the fusion. 

"Artist’s depiction of the IKAROS space probe ( the first spacecraft to successfully demonstrate solar sail technology in interplanetary space) in flight. Credit: Andrzej Mirecki" (ScitechDaily.com/Interstellar Travel: Magnetic Fusion Plasma Engines Could Carry Us Across the Solar System and Beyond)

3) Solar sails

Solar sails use solar wind or particle flow from the Sun to give thrust. The solar sail is the system that can use its sail or plate as the communication tool. But there are so-called active solar sail models. The base idea for those active solar sails is the same as in "Project Orion". "Project Orion" was a concept to plan a spacecraft that uses nuclear bombs to give thrust. 

In some models, researchers tie many solar sails to the front of the spacecraft. That thing can accelerate the craft's speed. And when the craft leaves the area where those systems can give thrust. The sails disconnect. And the craft continues by using some other propulsion systems. 

In some visions, solar sails would fly away from the solar system by using a trajectory where there is a hydrogen bomb at certain points in that trajectory. Those hydrogen bombs will detonate. And then they will give more thrust to those solar sails. In some other visions, giant lasers that orbit gas giants will shoot more energy for those solar sails. And maybe those kinds of systems travel to other solar systems.

"A spacecraft powered by a positron reactor would resemble this artist’s concept of the Mars Reference Mission spacecraft. Credit: NASA" (ScitechDaily.com/Interstellar Travel: Magnetic Fusion Plasma Engines Could Carry Us Across the Solar System and Beyond)

 

4) Positron reactors. 

In positron reactors cathode tubes shoot positrons and electrons to the impact course. The system shoots particles together in the rocket chamber. The remarkable thing is that this kind of system can make positrons get electricity to particle accelerators from the Sun. In this system, the solar panels can give electricity to particle accelerators that create positrons. 

Positron reactor spacecraft can look like a solar sail. The solar panels give electricity to cathode accelerators. That plate also acts as a solar sail, and the positron reactor gives thrust at a longer distance from the sun. And the solar sail structure helps to keep the temperature low. 

"Artist’s concept of a Bimodal Nuclear Thermal Rocket in Low Earth Orbit. Credit: NASA" (ScitechDaily.com/Interstellar Travel: Magnetic Fusion Plasma Engines Could Carry Us Across the Solar System and Beyond)

And finally. How to brake the rocket? 

The speed of those futuristic rockets is enormous. And those systems require brake rockets. In traditional systems, the probe uses an air brake. The probe flies through the planet's atmosphere. But in asteroid missions or missions to planets. Where there is no atmosphere the airbrake is useless. The craft requires brake rockets that slow its speed. There are two ways to make this bake. The first is simply to put the plate in exhaust gas.

Because the plate is connected to the craft, that engine's exhaust gas pushes the craft backward and slows its speed. The other version is to use forward-aimed rockets. 

Above: The NASA concept of a thermal nuclear rocket in low orbital might have two engine packs. The forward-aimed engines are for braking. The idea of brake rockets is to slow the speed of spacecraft so that it can put itself to a planet's or star's orbiter. The brake rockets are necessary tools in interstellar and interplanetary systems. For braking the spacecraft needs as much energy as it used for acceleration. So spacecraft can use half of its fuel for acceleration and half for slowing speed. 

https://scitechdaily.com/interstellar-travel-magnetic-fusion-plasma-engines-could-carry-us-across-the-solar-system-and-beyond/

https://en.wikipedia.org/wiki/Project_Daedalus

https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)

https://en.wikipedia.org/wiki/Tokamak

https://en.wikipedia.org/wiki/Zero-point_energy