Inertial Confinement Fusion- a brief Introduction

Reflections on fusion history, current events, and predictions for the 'fusion powered future.
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AshishGopalakrishnan
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Real name: Ashish Gopalakrishnan

Inertial Confinement Fusion- a brief Introduction

Post by AshishGopalakrishnan » Fri Sep 22, 2017 4:21 pm

Hello everyone, I wanted to share some brief info about the following topic:

Inertial Confinement Fusion (ICF) is an application involving shock waves, and is under deep research in the US. The ICF program is a part of the National Nuclear Security Administration (NNSA) and supports the Stockpile Stewardship Program (SSP) in providing experimental capabilities in High Energy Density Physics (HEDP). The ICF process involves a fuel target that is heated and compressed to initiate nuclear fusion. When high energy laser, electrons or ion beams hit the outer layer of the target, shock waves are generated. They travel inward thereby heating and compressing the fuel at the center and causing fusion reactions. Researchers have been trying to study the effects of hydrodynamic instabilities that accelerate the growth of non-uniformities on the target surface that can reduce the final compression and quench the ignition process. Instabilities in a system refers to infinitesimal velocity or density perturbances or any effect on the state of the system that is amplified by base or global forces and thus leads to growth of these infinitesimal perturbations to finite size as a result of impulse forces across the perturbed biomaterial interface. The system may depart from the initial state and may never return to that state. The Rayleigh-Taylor (RTI), Richtmeyer-Meshkov (RMI) and Kelvin-Helmholtz (KHI) instabilities are predominant and common in most hydrodynamic situations.

For those who might be interested can refer to this paper for more details and other good references on ICF:
R. Betti and A. Hurricane, “Inertial-confinement fusion with lasers,” Nat. Phys., vol. 12, no. May, pp. 435–448, 2016.

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Dennis P Brown
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Re: Inertial Confinement Fusion- a brief Introduction

Post by Dennis P Brown » Tue Sep 26, 2017 11:32 am

Very good post! I actually work in this field. Fusion using ion beams is, I think, the best way to go for ICF - makes sense no one has ever tried to do that approach in a serious effort (if you get my drift.)

AshishGopalakrishnan
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Real name: Ashish Gopalakrishnan

Re: Inertial Confinement Fusion- a brief Introduction

Post by AshishGopalakrishnan » Wed Sep 27, 2017 5:22 am

According to literature, there has not been a successful ignition of an ICF capsule and this is due to the dominating presence of hydrodynamic instabilities. These instabilities initially destroy the imploding shell, which greatly affects the formation of the central hot spot. The growth of the instabilities is known to increase exponentially with time. The on-going research focuses on coming up with solutions that could stabilize the growth of these instabilities, which is a critical factor in ICF applications. The research related to ICF is done in three National Labs namely, Sandia, Lawrence Livermore and Los Alamos.

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Dennis P Brown
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Re: Inertial Confinement Fusion- a brief Introduction

Post by Dennis P Brown » Wed Sep 27, 2017 4:56 pm

Yes, very slightly aware of these limitations for ICF since this is the work I happen to do. Glad it interests you. NIF claimed a "Scientific Break Even" and it is about five orders of magnitude from what any rational person would call "Break Even". And, of course, the wrong way on that ...lol.

ICF has many problems beyond what you sight and in fact, one of these might prove very serious - it is incoming beam scatter by plasma instabilities (yes, ICF has a plasma - blow off from the target) and it is looking to be an extremely serious issue. More tests should help to refine that rather "new" problem (was predicted in the past but only the more power systems today reached the energy densities on target that have started this type of instability to become apparent.) Always fun.

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