Living up to its name, University of Washington spin-off company ZAP Energy’s Century system is developing fusion power technology by blasting plasma with super-lightning-like pulses 12 times per minute, without relying on superconducting magnets or laser beams.
They say that there’s more than one way to skin a cat. The same goes for the pursuit of fusion conditions. While the preferred approaches use powerful magnets or arrays of lasers to confine and heat hydrogen isotopes until they fuse to release energy, there are other ways to achieve the same ends.
One of these is the Z-pinch principle, which was first developed for fusion experiments in the 1950s. In this, a column of plasma is pushed along the vertical or Z axis by a high-powered electrical current. This causes the plasma to self-generate a strong magnetic field at an angle that compresses and heats the plasma.
Century
Early experiments with the ZETA device in Britain in the 1950s appeared promising but it turned out that the plasma column was inherently unstable, which destroyed the confinement and cooled the plasma.
Things would have remained there and Z-pinch would have been an historical dead end, except that Dr. Uri Shumlak at the University of Washington in the 1990s found a way to overcome the instability issue by introducing a shear axial flow. This is where outer layers of the plasma column are propelled by a magnetic field so it moves faster than the plasma’s core. This causes a shearing force that disrupts the instability and keeps the column stable for long periods and even creates neutrons from genuine fusion of hydrogen atoms.
Century does not use deuterium-tritium isotope mix and its plasmas do not undergo fusion reactions or emit neutrons. It instead uses only simple hydrogen in the plasma, as ZAP Energy says the purpose of its Century platform isn’t to lead to an actual fusion reactor, but to gain more insights into Z-pinch and how to apply it to future technology.
ZAP Energy
During the record campaign, total input power was 57 kW, with 39 kW delivered to the cabling leading to the plasma chamber – a 20x increase in sustained average power over Century’s 2024 commissioning milestone. However, the clever bit isn’t the wattage, but the amperage, which is 500 kilo-amperes (kA) for each of the 0.2 Hertz (Hz) electrical pulses. According to the company, Century operated over 100 shots with one every five seconds or the equivalent, in current magnitude, of 12 “super-lightning” pulses per minute.
As a result, Century proved its capacity for repeated high-energy firing and showed that both the liquid-bismuth-lined chamber wall and the electrodes can endure the intense thermal and electrical stresses inside the device.
“Prolonged operations of a fully integrated, repetitively pulsed system at 30 kilowatts gives us a much clearer picture of what a sheared-flow Z-pinch fusion power plant will actually look like,” said Matthew Thompson, VP of Systems Engineering at Zap Energy. “Century’s real-world tests of our engineering subsystems mean we’ve already begun to identify and solve many of the most difficult commercial technology challenges.”
Source: ZAP Energy
