| Plasma Physics Seminar |
| January 29th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Open
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| February 5th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Open
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| February 12th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Open
|
| February 19th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Open
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| February 27th, Thu. 2:00PM
ERF 1207, Large Conference Room SPECIAL DATE AND TIME |
Darren Garnier, OpenStar
OpenStar Technologies: Developing the Levitated Dipole concept for fusion The levitated dipole fusion concept was proposed by Akira Hasegawa after observing Voyager 2's encounter with Uranus in 1986. Those observations confirmed that planetary magnetospheres have centrally-peaked density and pressure profiles that form naturally from turbulence driven by the solar wind. This remarkable property leads to several advantages of dipoles as fusion devices. Experiments at the Levitated Dipole Experiment (LDX), a joint Columbia/MIT project), showed over a decade ago that such profiles could be demonstrated in laboratory plasmas. Now, OpenStar Technologies, a fusion energy startup spun out of the high-temperature superconducting magnet group of Robinson Research Institute in Wellington New Zealand, is reviving the concept. The OpenStar team has constructed and are currently testing their first dipole, "Junior" with first plasma recently achieved. This LDX-scale device is designed to demonstrate much of the magnet technology required for dipole reactors and reproduce the results from LDX. The next generation machine, "Tahi", has goal of placing the dipole on the Lawson criterion curve of nT-tau, and demonstrating the theoretically decoupled nature of the energy and particle transport within a dipole confined plasma. This seminar will give an introduction to dipole confinement physics, previous experimental results, current operations on Junior, and requirements and initial designs for Tahi. |
| March 5th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Open
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| March 12th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Open
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| March 19th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Spring Break
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| March 26th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Abril Sahade, GSFC
The Challenging Life of Coronal Mass Ejections The Sun, as our closest astrophysical plasma laboratory, offers a unique opportunity to study extreme plasma behaviors with broad implications for both fundamental science and human technology. Coronal mass ejections (CMEs)-violent bursts of solar plasma and magnetic fields-are of particular concern due to their potential to disrupt satellite operations, communications, and spacecraft. Understanding the complex processes behind CMEs requires an integrated approach, combining remote observations, in-situ measurements, and advanced numerical modeling. In this talk I will address some key unresolved questions about the evolution of CMEs and discuss the coordinated efforts to answer them. |
| April 2nd, Wed. 3:30PM
ERF 1207, Large Conference Room |
Open
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| April 9th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Open
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| April 16th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Open
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| April 23rd, Wed. 3:30PM
ERF 1207, Large Conference Room |
Misha Padidar, Flatiron Institute
Towards Faster Prototyping of Stellarators Stellarators are a class of candidate fusion reactors based on magnetic confinement. The numerous design criteria and three-dimensional shaping of the magnetic field makes designing stellarators both time-consuming and computationally expensive. In this talk, we will show how the process of designing both the coils and the plasma can be reduced from hours on a cluster to just minutes on a laptop. To do this, we present a coil design paradigm for achieving magnetic confinement in stellarators with a pressure gradient. Our approach directly optimizes coil shapes and coil currents to produce a finite-beta quasi-symmetric magnetic field with a target rotational transform on the magnetic axis. |
| April 30th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Open
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| May 7th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Will Fox, University of Maryland
Experiments with magnetized laser-produced plasmas and plans for UMD experiments Postponed to next semester |
| May 14th, Wed. 3:30PM
ERF 1207, Large Conference Room |
Open
|
| May 21st, Wed. 3:30PM
ERF 1207, Large Conference Room |
Soumitro Banerjee, Institute
of Science Education & Research
Is our Sun going through a bifurcation? Astronomers have noticed that old sun-like stars rotate slower and have reduced magnetic activity than younger stars. The mechanism of magnetic braking of stars is well known, but it is a very slow process. Observational data indicate that there must be another mechanism that becomes active around the middle of a star's life, which renders the magnetic braking mechanism ineffective. There are indications that our Sun, at the age of 4.6 billion years, is now undergoing that `stellar mid-life crisis' because the 11-year solar activity cycle is exhibiting intermittent cycles of dormancy. Using a stochastic delay differential equation model of the mean magnetic field generation process in stars, we show that the phenomenon is caused by the existence of two attractors. As the sun ages, the system can come close to a saddle-node bifurcation point, where the periodic orbit representing the normal magnetic activity coexists with an equilibrium point representing a magnetically dormant state. When the two attractors are sufficiently close to each other, the system noise can intermittently knock the state from the periodic orbit to the equilibrium point and vice versa. These two solutions are possibly involved in the observed bimodal distribution of magnetic cycles in the Sun. On that basis, we argue that the Sun is right now undergoing a bifurcation that will eventually lead to the transition from a magnetically active to an inactive state. |
Contact Information:
Marc Swisdak
or
Ian Abel
