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| Fig. 1: Laser Bay 2, one of NIF's two laser bays. (Source: Wikimedia Commons) |
This article examines three major projects that address the reoccurring global energy crisis by attempting breakthroughs in nuclear fusion energy. Efforts by the United States of America led to the construction of the National Ignition Facility (NIF). The European Strategy Forum on Research Infrastructures (ESFRI) included the HiPER Project (European High Power laser Energy Research facility) in the European road map for Research Infrastructures. In 2006, the international community (China, Europe, India, Japan, Korea, Russia and United States) took the decision to fund the ITER Tokamak. The following sections detail each undertaking.
It has been nearly six years since the [National Ignition Facility] "NIF construction was certified by the Department of Energy as complete on March 27, 2009." [1] The NIF is a $4 billion complex the size of three football fields that is part of the Lawrence Livermore National Laboratory in Livermore, California, the scale of which is shown in Fig. 1. [2] Since initial testing began in 2009, the NIF has failed achieve one of its main goals, the ignition of nuclear fission.
In his article, "Why Has the National Ignition Facility Failed to Live Up to Its Name?", Michael Baumer has explained the roadblocks faced by the NIF team. [3] It is still too early to judge the success or failure of a project scheduled to test until the year 2040. However, it is safe to conclude that barring any miraculous turn of events in funding and/or other "technical hurdles", a world powered by fusion energy as a result of NIF experiments is nowhere near an actuality.
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| Fig. 2:The experimental hall at the ISIS neutron source at the Rutherford Appleton Laboratory in Oxfordshire, UK. (Source: Wikimedia Commons) |
In 2006, the HiPER Project (European High Power laser Energy Research facility) was included by ESFRI (the European Strategy Forum on Research Infrastructures) in the European roadmap for Research Infrastructures, aimed at following up the NIF's National Ignition Campaign of 2012 and prepare the way for future fusion reactors. [4] As part of the HiPER Project, a series of experiments related to fast ignition were performed at the RAL(UK)(see Fig. 3) and LULI (France) Laboratories and studied the propagation of fast electrons (produced by a short-pulse ultra-high-intensity beam) in compressed matter, created either by cylindrical implosions or by compression of planar targets by (planar) laser-driven shock waves. [4] Some goals and results of experiments conducted within the Working Package 10 (Fusion Experimental Programme) are detailed below. This, includes all the 'more technical' issues such as (i) the study of high-energy high-repetition laser drivers, (ii) the study of target mass production, injection, tracking and position at high-repetition frequency, (iii) studies on chamber design, material resistance, material activation, etc, at high radiation fluxes, etc.
However, fusion does not only involve technological problems. Before that, there is also a very important physical problem: NIF ignition will indeed be based on indirect drive (ID), which does not seem to be compatible with the requirements of future fusion reactors. Indeed ID requires (i) complicated targets, (ii) massive targets injecting a lot of high-Z materials in the chamber, and above all (iii) it is intrinsically a low gain approach due to the intermediate step of x-ray conversion. In addition, ID poses several "political" problems connected to proliferation issues and classification.
Therefore we need to investigate the direct drive (DD) approach in order to achieve higher gains and allow for simpler reactor schemes. Unfortunately the scientific problems connected to DD drive are today not solved. Pursuing the DD approach implies studying (i) the hydrodynamics of target implosions and methods for smoothing of non- uniformities, and (ii) the possibility of realizing "advanced ignition" schemes which may guarantee even higher gains while relaxing the constraints on target and irradiation uniformity (and also make fusion possible with smaller facilities). The two advanced ignition schemes, which have been proposed in the recent past, are (1) fast ignition and (2) shock ignition.
Within this context, the goals (and the problems) of WP10, as well as of other WPs, have been the following:
To perform experiments addressing relevant questions on the physics related to ICF [inertial confinement fusion], taking into account the limitations of existing laser systems in Europe (and also across the world).
To build a scientific community in Europe working not just on "laser plasmas" but also on ICF-oriented issues. In particular, learn together how to realize lengthy and difficult, programmatic experiments.
To address experimental issues where we have little competencies (or have lost them), i.e. hydrodynamics, instabilities, implosions, etc.
To prepare collaborations with US and Japan, and realize the first collaborative experiments.
To make the European community "credible" in face of the international community, while maintaining the European leadership where we have it (i.e. ultra-high-intensity laser-plasma interactions). [4]
The HiPER Project does more than point out the technical and physical issues of current laser and NIF designs. Outlined is a psuedo set of five commandments for more countries to participate in funding research for fusion experiments and commit to solving existing problems. Represented is a strong desire for the UK and France to remain relevant on the fusion science landscape.
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| Fig. 3: Map showing (roughly) the location of the Cadarache research center. (Source: Wikimedia Commons) |
In 2006, the international community took the decision to fund the ITER tokamak, to the tune of around 10 billion euros. [5] This device will use magnetic fields to confine a large, low-density plasma in a quasi-steady state, such that it releases more energy than it consumes. In 2011, construction of ITER has started at the Cadarache site in southern France illustrated in Fig. 2. The first buildings complete and more than 60% of the in-kind procurement has been committed by the seven ITER member states (China, Europe, India, Japan, Korea, Russia and United States). [6] Responsible for the preparation and leveling of the site was Agence ITER-France. "Preparatory work on the ITER site started at the beginning of 2007 and the levelling of the 40 ha platform is now complete. [7] In addition, infrastructure such as access roads, drainage pipes, etc. is nearing completion. The detailed design and construction of ITER building is being carried out by Fusion for Energy (F4E), a Europen Domestic Agency based in Barcelona, Spain. [7] When complete the site will house dozens of concrete and steel frame buildings needed for ITER.
Given the collective efforts to gain a positive energy return using lasers or magnetic fields in fusion, one major barrier still exists. Fusion energy has not been achieved on a large scale partly because the materials that can with stand the bombardment of neutrons and hot plasma has not been invented yet. This fundamental oversight by the collective scientific community was highlighted by Professor Sebastien Balibar in Matt McGrath's BBC article. Professor Balibar explained, "that fusion is like trying to put the Sun in a box [...]. [8]
Many may paint a grim picture for the future of fusion energy however it is important to keep in mind the historical context of what is being attempted. Political pressure and financial restraints may impose on the will of the short-sighted individual who has no concern for the state of the world after his or her own demise. As scientist slowly inch closer to making a fusion energy reality, it is important for the global community to applaud their efforts and encourage more progress. Progress may be decades into the future, however the groundwork laid in today's times will determine the status of the energy situation for our great-grandchildren and the generations that follow.
© David Davis. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] E. I. Moses, "The National Ignition Facility and the National Ignition Campaign," IEEE Trans. Plasma Sci. 38, 684 (2010).
[2] J. Mandel, "National Ignition Facility Prepares for Fusion Test," Scientific American, 20 Aug 09.
[3] M. Baumer, "Why Has the National Ignition Facility Failed to Live Up to Its Name?" Physics 241, Stanford University, Winter 2015.
[4] D. Batani et al., "The HiPER Project For Inertial Confinement Fusion and Some Experimental Results on Advanced Ignition Schemes," Plasma Phys. Control. Fusion 53, 124041 (2011).
[5] N. Holtkamp, "The Status of the ITER Design," Fusion Eng. Des. 84, 98 (2009)
[6] A. Wallander et al., "News from ITER Controls - A Status Report," ITER Organization, 2011.
[7] K. Ikeda, "ITER on the Road to Fusion Energy," Nucl. Fusion 50, 014002 (2010).
[8] M. McGrath, "Fusion Falters Under Soaring Costs," BBC Newes, 17 Jun 09.
