New accelerator to examine heavy-ion-beam approach

June 25, 2012
An overhead view of the NDCX-II. Photo by Roy Kaltschmidt/Lawrence Berkeley National Laboratory

The Department of Energy's Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL), whose member institutions include LLNL, Lawrence Berkeley National Laboratory (LBNL) and the Princeton Plasma Physics Laboratory, has recently completed a new accelerator designed to study an alternate approach to inertial fusion energy.

Housed at LBNL, NDCX-II is a compact machine designed to produce a high-quality, dense beam that can rapidly deliver a powerful punch to a solid target. Research with NDCX-II will introduce advances in the acceleration, compression and focusing of intense that can inform and guide the design of major components for heavy-ion fusion energy production.

NDCX-II is an induction accelerator that can handle compact pulses of some 200 billion positively charged lithium ions, shaping each pulse as it is accelerated, and making sure that almost all the ions are delivered to the target within a nanosecond. But when they start from the injector, the ions are spread out in a 500-nanosecond pulse; the first task of the accelerator is to set the pulse's tail moving faster than its head. Then, during the initial acceleration, the overall pulse length shortens to less than 70 nanoseconds.

After further acceleration, the pulse enters a drift tube filled with plasma, which neutralizes the mutually repulsive charge of the positive ions and allows the pulse to compress, as its faster-moving tail closes the final distance to the head while focusing on the target. This process of neutralized drift compression gives the machine its name.

LLNL's HEDLP/Heavy group within Physics Division's Fusion Energy Sciences Program developed most of the physics design for NDCX-II, under an $854,600 subcontract to LBNL. LLNL also provided the accelerating cells, which were previously used for its Advanced Test Accelerator (ATA), and the Blumleins, which are 250,000-volt, pulsed-power sources that provide the rapid final acceleration.

In addition to providing the ATA cells and Blumlein power sources, LLNL led the development of the beam dynamics prescription and the "acceleration schedule" (sequence of shaped accelerating waveforms, including specification of their shapes, amplitudes, timing and placement of the active accelerating cells on the beamline). Lab scientists also contributed to other aspects of the machine, such as the prescription for locating the beam "steering" components and establishment of the optimal beam-pipe size.

"NDCX-II represents the first conversion of electron induction accelerator components into a pulse-compressing ion accelerator," said Alex Friedman, the project's beam acceleration task area leader. "It would not have been possible without the tri-lab collaboration of the HIFS-VNL. With NDCX-II we will be able to study fusion-relevant intense-beam physics, ion-heated matter properties and elements of target physics for ion-beam-driven inertial ."

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1 / 5 (1) Jun 25, 2012
Nice approach. Now this design could also be used for space propulsion, and maybe if compact enough for a true space shuttle.... Too far ahead? Look again! The beam supplies a punch to a reaction chamber, generating fusion energy at a target. The resultant will be a beam of much greater intensity with the added newly generated fusion the same direction as steered down a electromagnetodynamical energy recovery tube on its way to secondary recovery. Here would be the departure of propulsion use from pure planetside use. The output of the recovery tube becomes the 'rocket engine' with a very high energy output per fuel consumption quantity ratio, thousands or more times that of the so called best offering from the bloated oil industry. And environmentally safer as well. Can envision assemblies of this type producing hundreds of millions newtons of thrust and opening space to our species at last. Oil rockets are giant kerosene space heaters...and just as dirty!
not rated yet Jun 25, 2012
Could work, but the best rockets are not oil derived, but hydrogen/oxygen which only spits out water when combined. You can't get much more environmentally friendly than that.

Like you said, they have to make it smaller and more importantly, much much lighter. If the fusion ignites, you would have a powerful rocket.
5 / 5 (1) Jun 25, 2012
I dont care how efficient your rocket is, if the thrust/weight is < 1, you dont have a rocket.

maybe if compact enough

yeah, and maybe if i dont die, I'll live forever. saying it doesnt make it easy.

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