02.08.2013 Views

Research Needs for Magnetic Fusion Energy Sciences - US Burning ...

Research Needs for Magnetic Fusion Energy Sciences - US Burning ...

Research Needs for Magnetic Fusion Energy Sciences - US Burning ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

4. based on the outcome of actions 1-3, a new experiment capable of demonstrating the<br />

integration of confinement, current sustainment, active control of mhd stability, and<br />

boundary control is essential to establish the scientific basis <strong>for</strong> an RFP burning plasma.<br />

This could be a two-stage, upgradeable facility that first emphasizes the integration of<br />

confinement and current sustainment at moderate plasma current. a 2 ma first stage<br />

could attain sufficiently high-S to robustly test confinement scaling, ac current drive,<br />

and the hybrid scenario. The second stage will push per<strong>for</strong>mance at the 4 ma level to<br />

test confinement and current-drive up to S=10 9 and r* less than 1% with fully integrated<br />

boundary control and near-burning plasma conditions. The pulse length requirement<br />

<strong>for</strong> both stages will demand active control of resistive wall modes (RWms). high-power<br />

plasma control using mW-level neutral beams and radiofrequency are required, and the<br />

experiment must be well-diagnosed to validate our understanding of the important<br />

physical processes.<br />

similar to the RFP, spheromaks have shown transient control of magnetic fluctuations leading to<br />

electron temperature of 0.5 kev and core energy confinement time of 10 ms. continuous sustainment<br />

compatible with good confinement has not been demonstrated and is a focus of near-term<br />

activities. at present there are no large-scale experiments that can address this issue or other limits<br />

to confinement. The development path shown in Figure 2 will fill this gap, facilitate innovation<br />

to increase <strong>for</strong>mation efficiency, and address technology needs.<br />

1. Upgrades of existing and construction of new ce-level experiments will foster innovation<br />

in <strong>for</strong>mation and current drive studies. With support from analytics and computation,<br />

<strong>for</strong>mation experiments will investigate methods <strong>for</strong> exceeding the flux amplification and<br />

current multiplication factors obtained in past experiments. They will also improve our<br />

understanding of mhd activity excited by ac current drive and refluxing techniques <strong>for</strong><br />

steady, quasi-steady, and pulsed operation.<br />

Figure 2. CE spheromaks emphasize innovation to address specific needs prior to PoP development.<br />

384

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!