Brice N. Cassenti

Plasma Heating by Antiproton Annihilation in Magnetic Mirror Fusion Propulsion

Magnetic mirror fusion propulsion shows promise as a means for opening up interplanetary travel. The systems, though, tend to be large and heavy. One of the heaviest components in the system is the plasma heater. Heating by the annihilation of antiprotons in the plasma could result in a considerable reduction of mass. An examination of various heating sources in the annihilation reaction show that most of the heating may not be effective. Although, heating by the relativistic electrons may be useful the plasma chamber radius and lengths may have to be increased. An indirect heating method, where antiprotons are annihilated in a fissionable material, such as uranium- 238, may be useful. The resulting fission products are then used to heat the plasma, which should be more efficient.

Future of Antiproton Triggered Fusion Propulsion

Antiproton triggered fusion propulsion appears to be a promising method for achieving high specific impulse and high thrust in a nuclear pulse propulsion system. In antiproton triggered fusion systems the antiprotons are injected into a pellet containing fusion fuel with a small amount of fissionable material. The fission fragments resulting from the annihilation of antiprotons are used to trigger a fusion reaction. Initial estimates indicate that if magnetically insulated inertial confinement fusion is used that the pellets should result in a specific impulse of between 100,000 and 300,000 seconds at high thrust. The engineering problems that must be overcome are significant. Among the challenges the most difficult may be the precise focusing of the antiprotons required to generate extremely large magnetic fields. Other challenges include the pellet design necessary to contain the fission and initial fusion products which will also require strong magnetic fields. The fusion fuel must also be contained for a sufficiently long time to effectively release the fusion energy, and the payload must be shielded from the radiation, especially the excess neutrons emitted, in addition to other particles.

Engineering Challenges in Antiproton Triggered Fusion Propulsion

During the last decade antiproton triggered fusion propulsion has been investigated as a method for achieving high specific impulse, high thrust in a nuclear pulse propulsion system. In general the antiprotons are injected into a pellet containing fusion fuel with a small amount of fissionable material (i.e., an amount less than the critical mass) where the products from the fission are then used to trigger a fusion reaction. Initial calculations and simulations indicate that if magnetically insulated inertial confinement fusion is used that the pellets should result in a specific impulse of between 100,000 and 300,000 seconds at high thrust. The engineering challenges associated with this propulsion system are significant. For example, the antiprotons must be precisely focused. The pellet must be designed to contain the fission and initial fusion products and this will require strong magnetic fields. The fusion fuel must be contained for a sufficiently long time to effectively release the fusion energy, and the payload must be shielded from the radiation, especially the excess neutrons emitted, in addition to many other particles. We will review the recent progress, possible engineering solutions and the potential performance of these systems.

Antiproton triggered fusion propulsion for interstellar missions

Interstellar precursor missions have been the subject of recent investigations. Current proposals include a thousand and a ten thousand astronomical unit mission, both to be completed in fifty years. These interstellar precursor missions provide a means to develop payload, communication, guidance and propulsion systems that could ultimately send payloads to the stars. The one thousand astronomical unit mission could be completed by improvements in nuclear electric systems, but the ten thousand astronomical unit mission is considerably more difficult. Antiproton triggered fusion propulsion systems provide a means to develop fusion propulsion in the near term. These systems rely on antiprotons to fission a subcritical mass of uranium or plutonium. The energy released in the fission reaction is then used to trigger fusion in a pellet. A 1000 astronomical unit mission can be completed in 50 years with a mass ratio of 1.06, while for a 10,000 astronomical unit mission the ratio is 1.87. A flyby of the nearest ...

MICF: A fusion propulsion system for interstellar missions

A very promising propulsion device that could open up the solar system and beyond to human exploration is the Magnetically Insulated Inertial Confinement Fusion (MICF) system. This scheme combines the favorable aspects of inertial and magnetic fusion into one where physical containment of the hot plasma is provided by a metal shell while its thermal energy is insulated from this wall by a strong, self-generated magnetic field. The fusion nuclear reactions in this device can be triggered by a beam of antiprotons that enters the target through a hole and annihilates on the deuterium-tritium (DT) coated inner wall giving rise to the hot fusion plasma. In addition to thermally insulating the plasma, the magnetic field helps to contain the charged annihilation products and allows them to deposit their energy in the plasma to heat it to thermonuclear temperatures. Preliminary analysis given in this paper shows that an MICF propulsion system is capable of producing specific impulses on the order of 106 seconds. ...

An antiproton‐driven magnetically insulated inertial fusion propulsion system

The magnetically Insulated Inertial Confinement Fusion (MICF) reactor, in its initial conception, concepts of a target in the form of a metal shell whose inner surface is coated with a fusion fuel which is ignited by an incident laser beam that enters the pellet through a hole. A very strong magnetic field, generated when the surface is ablated by the incident laser beam, provides thermal insulation of the wall from the hot plasma, and allows the plasma to burn longer thereby generating a larger energy amplification. When ejected through a magnetic nozzle the plasma can provide a very large specific impulse if MICF is utilized as a propulsion device. For application to space travel, however, the mass of the laser and associated power supply may prove to be prohibitively large and another driver should be considered in its place. In this paper we examine the potential use of antimatter annihilation reactions along with a fissionable component to generate the energy needed to initiate the fusion reactions. ...