How do Z pinches contribute to groundbreaking research?
In order to fuse the atoms, the force that repels them as they come together must be overcome. Accelerators accomplish this by forcing molecules to collide with one another at very high temperatures (high temperatures are simply molecules moving at high speeds).
When light nuclei are involved, fusion can produce more energy than was required to start the reaction. This process is at work in nature in the Sun, for example, whose source of energy is an ongoing fusion chain reaction.
As an unconfined event, fusion has long been used in the development of weapons. But its great potential as a new source of energy, which depends on scientists’ ability to harness its power in confined laboratory events, continues to be explored. The Z machine is central to that effort.
The major challenge for fusion researchers is to figure out a way to contain a hot plasma – hot enough to melt any container – for long enough to get energy out. Scientists are attempting to do this mainly in one of two ways. One approach involves confining a low-density plasma for a long time using magnetic fields, which don’t melt. This approach is known as magnetic confinement fusion. The other major approach works under the assumption that a plasma cannot be contained for long. The goal, then, becomes creating a series of bursts of energy, getting as much energy as possible out of a small, high-density plasma before it expands and cools. This is what is known as internal confinement fusion, and this is the main approach used at Z.
In their study of fusion, Z researchers work with every aspect of a carefully designed process. Inertial confinement fusion involves a BB-sized fuel capsule placed inside a container about the size of a spool of thread. An enormous pulse of power is focused for a few nanoseconds on the fuel capsule containing a mixture of hydrogen isotopes (deuterium and tritium). The source of power is often a laser, or in the case of the Z machine, a Z pinch. Whatever the source, the intense burst of power causes the target to implode, compressing the material in it and heating it to temperatures near those at the center of the sun. If the heat and pressure are intense enough, the conditions should ignite a fusion reaction.
For years fusion work with Z has been sought primarily for weapons effects simulations, weapons physics, and other scientific purposes, but there is a synergy between that kind of research and the potential energy applications of fusion. Fusion research for weapons and fusion research for energy share many of the same basic physics issues, and high-yield fusion in the laboratory would translate into progress in both areas.