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Plasma Physics (Physics/ECE/NE 922) Seminars

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First plasma experiments in WHAM
Date: Monday, September 9th
Time: 12:05 pm - 1:00 pm
Place: 1610 Engineering Hall
Speaker: Dmitry Yakovlev, University of Wisconsin-Madison
Abstract: In this talk, I will provide a brief introduction to the Wisconsin Axisymmetric HTS Mirror (WHAM), a groundbreaking magnetic confinement experiment recently constructed and launched at UW-Madison. This experiment features record-breaking 17 Tesla superconducting mirror magnets and a variety of plasma heating systems, achieving a total heating power density of up to 50 MW/m³. This unique combination of parameters enables a wide range of mirror confinement studies that were not possible previously.

I will discuss the unique engineering solutions implemented in the machine’s design, along with insights gained from its assembly and initial operation. Drawing from my experience with large mirror experiments, I will highlight critical research topics that could advance us toward practical fusion applications.

During the first experimental campaigns, WHAM achieved a successful ECR breakdown, consistently producing plasma at power levels as low as 10 kW of 110 GHz microwave radiation, and with densities exceeding 1019 m-3. Several observed effects, such as density saturation and dependency on prefill pressure, align well with published data, while others – much higher diamagnetic flux (0.4 mWb), hot electrons with confinement time of ~ 1 s and indications of intense MHD activity during ECH are reported for the first time. Initial experiments with 22 keV deuterium neutral beam injection demonstrated beam attenuation of > 50%, although the fast ion confinement time is currently limited by high charge-exchange losses.

I will cover these findings and outline near-term experimental plans aimed at advancing the experiment’s scientific goals.
Host: Cary Forest
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