Fusion Power:

Science moves a step closer

Report by

COSR: SFS – SFC DCOSR: SFS-SFC

For a greater part of the twentieth century, research into the viability of fusion power has been achieved only in the detonation of the hydrogen bomb. And though the hydrogen bomb is proof that such is feasible, control of the result has yet to be mastered.

One such way is by use of a magnetic containment field, which had been achieved, back in the early 1990’s at the Princeton University’s Tokamak Fusion Test Reactor. However, the amount of energy required outweighed the proposed benefits.

Another method was to use an intense laser to ignite the hydrogen pellets, thus commencing ignition. However, once more the power required to effect such was enormous, one hundred terawatts, [or one hundred trillion watts], the equivalent of condensing several hours worth of power used by half a dozen homes into a matter of a fraction of a second.

To accommodate this immense need for power, a system coined ‘pulse power’ was developed. This method stored electrical energy in capacitors, which were then ‘discharged’ in brief pulses to fire the devices necessary for ignition. However, the technique had limited power output, thus rendering it too expensive for commercial use.

Research into the problem has determined that the power required for full ignition to be five hundred terawatts and two million joules of radiation heated to a temperature of three million degrees for a period of four nanoseconds. Such can be done with lasers, however the power require to operate the laser is greater than the expected output of the fusion reaction.

Fusion reaction devices HAVE achieved power outputs reaching three hundred terawatts, using a concept called the Z-pinch, an offshoot of the magnetic containment research.

Using deuterium gas, and passing a strong electric current through it, the gas is ionized and a magnetic field is generated which ‘pinches’ the resulting plasma to high temperature and density along the currents path. Used to initiate inertial fusion, and combined with fast pulsed power, we are one step closer to a practical fusion reactor.

To trigger the fusion process, the Z-pinch must be enclosed in a chamber referred to as a ‘Hohlraum’ (the German word for cavity or hollow); currently there are two methods being explored as a means of achieving this.

Many methods were also considered in an effort to make the plasma more uniform (earlier the plasma stream was far too unstable to successfully achieve fusion). A solution was found in the use of numerous fine tungsten wires, which form a ‘plasma shell’ around the igniting pellet. Subsequent research has shown that the wires do not turn completely to plasma all at once, instead a cold core of wire may remain, allowing the current flow to continue for a time and thus increasing the efficiency of the pinch.

In the latter half of the last decade of the twentieth century, research has moved much closer to the goal of reaching the temperatures necessary for high-yield fusion. As a side note, the current research and development already achieved has possible applications in astrophysics, atomic physics, and x-ray lasers.

Further updates on the progress of this research will be forwarded, as they become available.