What’s New

A senior researcher at MIT's Plasma Science and Fusion Center (PSFC) in the US is using a gyrotron, a specialized radio-frequency (RF) wave generator developed for fusion research, to explore how millimetre RF waves can open holes through hard rock by melting or vaporizing it.

Penetrating deep into rock is necessary to access virtually limitless geothermal energy resources, to mine precious metals or explore new options for nuclear waste storage. But it is a difficult and expensive process, and today's mechanical drilling technology has limitations. Woskov believes that powerful millimetre-wave sources could increase deep hard rock penetration rates by more than ten times at lower cost over current mechanical drilling systems, while providing other practical benefits.

"There is plenty of heat beneath our feet," he says, "something like 20 billion times the energy the world uses in one year." But, Woskov notes, most studies of the accessibility of geothermal energy are based on current mechanical technology and its limitations. They do not consider that a breakthrough advance in drilling technology could make possible deeper, less expensive penetration, opening into what Woskov calls "an enormous reserve of energy, second only to fusion: base energy, available 24/7."

Current rotary technology is a mechanical grinding process, limited by rock hardness, deep pressures, and high temperatures.  Specially designed "drilling mud," pumped through the hollow drill pipe interior, is used to enable deep drilling and to remove the excess cuttings, returning them to the surface via the ring-shaped space between the drill pipe and borehole wall. The pressure of the mud also keeps the hole from collapsing, sealing and strengthening the hole in the process. But there is a limit to the pressures such a borehole can withstand, and typically holes cannot be drilled beyond 30,000 feet (9km).

Woskov asks, "What if you could drill beyond this limit? What if you could drill over ten kilometers into the earth's crust?" With his proposed gyrotron technology this is theoretically possible.

Continue reading on the PSFC website.

The ASDEX-Upgrade team at the Max Planck Institute for Plasma Physics (IPP) in Garching, Germany is experimenting with a new mode of tokamak operation.

In recent experimental results, an operational mode described as offering "stable plasma, high plasma pressure and good confinement properties in a parameter range in which future power plants are to be working" has been achieved almost without the transformer, or solenoid, that is typically used to induce the strong current in the plasma that contributes to creating the magnetic cage of tokamaks like ITER and ASDEX-Upgrade.

In its place, microwaves and particle beams injected close to the plasma core were used to prolong the plasma pulse.

This type of "advanced tokamak operation" was the object of investigation for IPP scientist Alexander Bock, who details the advantages that continuous operation would have over pulsed operation as part of his PhD thesis. Advantages included better control of the plasma current profile in the plasma, longer pulses, and decreased turbulence.

Read the IPP press release in English or in German.