Good news! How many more years before humans can create the power of the sun on earth? Don't trash or mothball your solar panels yet! 😊
"Seeking to improve the tokamak fusion reactor known as ITER, researchers have found a way to stop ... tungsten atoms from shearing off the walls and messing with the plasma. The finding is another important milestone on fusion's road to success. ...
They found that injecting boron powder into the reactor shields the tungsten walls from the ravages of the plasma and allows it to hold on to all of its atoms. ..."
"... But under the intense heat of fusion plasma, tungsten atoms from the wall can sputter off and enter the plasma. Too much tungsten in the plasma would substantially cool it, which would make sustaining fusion reactions very challenging.
Now, researchers ... have experimental results suggesting that sprinkling boron powder into the tokamak could solve the problem. Boron partly shields the reactor wall from the plasma and prevents atoms from the wall from getting into the plasma. A new computer modeling framework ... shows the powder may only need to be sprinkled from one location. ..."
From the abstract:
"The ITER Organization (IO) is proposing to change to full tungsten plasma facing components. As risk mitigation to achieve and sustain Q=10, the IO has proposed real-time solid boron injection (SBI) during plasma operation to supplement gaseous discharge boronization (GDB). Boron getters oxygen and reduces tungsten sputtering. In areas with significant plasma wall interactions, boron coatings are expected to be short-lived at high plasma performance. The system should be used sparingly, as boron redeposition retains tritium, which must be minimized in ITER to comply with nuclear safety. SBI can limit and precisely control the amount of boron injected. Some design requirements and concepts for SBI in ITER will be presented based on results with pellet injection or granule dropper systems installed at or by PPPL on machines around the world. Boron from 5 µm – 2 mm diameter was injected at calibrated rates of 2 – 200 mg/s during plasma operation on AUG, DIII-D, EAST, KSTAR, LHD, TFTR, WEST, and W7-X, to improve wall conditions and plasma performance. The boron is ionized in the plasma edge and then deposited on plasma-wetted surfaces. Reduced tungsten sputtering was observed following discharges with SBI on AUG, EAST, and WEST. Experimental SBI results will be compared with modelling of erosion and redeposition of boron to attempt to quantify the amount of boron needed and if one SBI location is sufficient in ITER. SBI control requirements and operation scenarios for ITER will also be described."
Stopping off-the-wall behavior in fusion reactors "Boron could help the tungsten wall inside a tokamak keep its atoms to itself"
This drawing of a cross section through ITER shows the pellet injection guide tubes and a sketch of a conceptual design for a boron dropper.
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