A Plan to Develop Inertial Fusion Energy

J.D. Lindl, W.R. Meier, S. A. Payne -- Lawrence Livermore National Lab

J.D. Sethian, S. P. Obenschain -- U.S. Naval Research Lab

B.G. Logan, Lawrence Berkeley National Lab

E.M. Campbell, J.P. Dahlburg -- Genral Atomics

C.L. Olson, M.K. Matzen, Sandia National Lab

September 27 , 2002

**I. Introduction**

Fusion powers the sun and the stars. If fusion could be harnessed on
earth, the power plant would have a virtually unlimited supply of fuel
(Every barrel of sea-water contains a few grams of fusion fuel with the
energy equivalent of over 300 barrels of oil). Fusion would produce no
chemical pollution or greenhouse gases, and it would be inherently safe
(the fuel can neither "blow up" or "melt down"). With a successful
materials development program, fusion chambers can be designed whose
radioactivity would be minimal in volume, toxicity, and life time so
that there would be no need for massive geological repositories. A
fusion power plant could also produce hydrogen for its many uses
including petrochemicals and fuel cell powered transportation, thus
reducing our dependence on foreign oil. In short, fusion would give the
world a clean, environmentally attractive, universally available source
of energy for the numerous applications of central power production for
the indefinite future.

Sufficient scientific and technical progress has been made in fusion
research that a plan can be confidently formulated to deliver fusion
power to the electric grid in 35 years or less. The plan here addresses
the development path for *Inertial Fusion Energy (IFE),* in which
repetitive pulses of energy rapidly compress and heat a small target
containing the fusion fuel. An alternative approach, called *Magnetic
Fusion Energy (MFE),* uses magnetic fields to continuously confine and
heat the fusion fuel. Plans for the development of magnetic fusion
energy will be presented in a companion document. IFE and MFE have
different strengths as well as scientific and engineering challenges.
Developing these two approaches together will provide a robust approach
and is a strategic impearative that substantially increases the chance
for successful development of economically competitive fusion energy.

A focused and appropriately funded program in inertial fusion energy
could field an engineering test facility (ETF) within 20 years. An ETF
would provide an integrated test platform and develop the final
scientific, materials and engineering concepts prior to building a
demonstration power plant for the commercial application. In some
configurations the ETF itself could be used to demonstrate fusion power
production after completing its research tasks.

This plan leverages the major investment of the National Nuclear
Security Administration (NNSA) in developing the fundamental science of
inertial confinement fusion (ICF) as part of the US Stockpile
Stewardship Program. The goal of ICF research in NNSA is controlled
laboratory implosion of fusionable material to a condition of ignition
and propagating burn -- a key scientific issue regarding the feasibility
of IFE. The enery input for this objective is comparable to that
envisioned for an IFE power plant. The further goal of IFE research is
economic production of safe, reliable energy from the ICF process in
quantities suitable for practical commercial application.

As a result of the NNSA investment, the inertial fusion community in the
United States is well and uniquely poised to meet this challenge of
achieving fusion energy. There is already a large, robust, balanced
theory and experiments program that supports the scientific feasibility
for inertial fusion. The National Ignition Facility (NIF), an NNSA
facility scheduled for completion in 2008, is tasked with achieving
thermonuclear ignition with laser compressed targets. This is the
scientific equivalent of the "burning plasma" facilities being proposed
for the MFE community. Another large pulsed-power z-pinch device at
Sandia National Laboratory has been extraordinarily successful in
producing large quantities of x-rays to drive capsule implosions. If
scaled to a larger device these x-rays, could, in theory, compress
targets that ignite. In addition, the US is the world leader in all the
most promising pulsed energy sources, or "driver technologies" needed to
progress from the present research facilities to power plants. The
drivers include: krypton-fluoride lasers, diode pumped solid-state
lasers, the induction linac for heavy ion acceleration, and repetitive
pulsed power technologies for z-pinch drivers.

The ICF community has had long term experience integrating large scale
experiments where one must simultaneously deal with matching precise
target, experiment and driver requirements. This "systems approach" has
since been adapted to the more demanding requirements for inertial
fusion energy. The IFE community has developed integrated complementary
plans for the staged development of inertial fusion science, as well as
the driver, target and power plant technologies.

There are three main concepts for Inertial Fusion Energy based on ion
beams, lasers or repetitive pulsed power. All three hold great promise
for an attractive power plant, but all three must also resolve
significant technical challenges. Thus it is premature and unwise to
down- select an approach at this time, and a balanced program is
required. Each concept is on its own development path with three
distinct phases: Phase I) basic science and technology development,
Phase II) full scale technology development, and Phase III) an
integrated engineering test facility (ETF) which would demonstrate that
the concept can generate repetitive fusion power. Specific goals and
milestones must be met before advancing from one phase to the next. Each
phase represents increasing confidence, decreasing technical risk, and
increasing cost. The ETF program, with proper funding, could start
within 10-15 years.

In addition to the three main approaches, inertial fusion also includes
less developed, high risk but high pay-off concepts, such as the Fast
Ignition target concept discussed below, that deserve exploration. The
modularity and flexibility of inertial fusion would in principle enable
such advanced features to be added at minimal cost to the mainline
approaches.

In order to implement this Inertial Fusion Energy Development plan,
there needs to be both a proper management structure in the Department
of Energy and sufficient resources.

1.  Management structure: Although NNSA's investment in ICF has
    precipitated enormous US progress in the design of the targets and
    drivers, NNSA has not yet embraced an energy mission. Thus the R&D
    needed for key power plant issues are unsupported. The Office of
    Fusion Energy Science (OFES), while supporting some IFE work, has
    directed the majority of its resources and management focus on MFE
    sciences. As a result, the inertial fusion energy community's
    pursuit of a coherent, energy-oriented program is hindered by the
    lack of "ownership" on the part of DOE. This could be solved with an
    organization which embraces Inertial Fusion Energy as a central
    goal.

2.  Resources: While a detailed budget is outside the scope of this
    document, an IFE development plan with the goal of putting
    electricity on the grid in less than 35 years will cost about \$100
    M per year in the early stages, and about \$200 M per year as some
    of the more advanced concepts enter Phase II. The ETF will be a
    multi- billion dollar class nuclear facility and it is anticipated
    that only the most promising concept will be carried to this phase.

**II. Overview of Inertial Fusion Energy**

An IFE power plant will produce energy by focusing intense short bursts
of laser light, charged particles, or x-rays onto a small target
containing fusion fuel. In current targets the fuel contains a frozen
mixture of deuterium and tritium, which are both isotopes of hydrogen.
(Deuterium comes from sea-water. Tritium is created when neutrons from
the fusion reaction interact with lithium, which is a plentiful element
in the earth's crust and in sea water.) The intense energy from the
driver compresses the fuel to fusion conditions for density and
temperature, whereupon it ignites with a burst of fusion reactions
releasing much more energy than was invested. The power plant of the
future will consist of a "fusion core" and the "balance of plant".
Depending on its purpose, this balance of plant could, for example, be a
power conversion unit to produce electricity, or a hydrogen production
plant. The fusion heart of the power plant will have several important
systems:

> 1\. The fusion targets containing the fuel.
>
> 2\. A factory designed to fabricate millions of targets per year.
>
> 3\. A chamber approximately 6 meters or more in diameter to capture
> the energy produced by the fusion pulses.
>
> 4\. A system to inject or place the targets into the chamber.
>
> 5\. A driver to produce the ions, laser or x-ray energy needed for
> ignition.

6\. A focusing or concentration system to deliver the driver energy to
the target.

There are several advantages to Inertial Fusion Energy:

1.  The systems are spatially separated. For example the driver and
    target factory are many meters away from the chamber and can be
    isolated and protected from the fusion energy release.

2.  The systems are modular and to a large part independent. Thus the
    phenomena that control target energy gain, chamber repetition rate,
    and power plant reliability can be studied independently. This
    significantly lowers development costs. More importantly, it allows
    economical upgrades in a working power plant.

3.  Inertial fusion energy does not require the construction of an
    additional "burning plasma experiment" to establish the basic
    scientific feasibility. IFE can obtain the needed scientific data on
    burning plasmas from the National Ignition Facility (NIF) currently
    under construction at Lawrence Livermore National Laboratory. Also,
    IFE is currently obtaining essential physics data on a wide variety
    of target concepts from existing NNSA facilities such as Z, Omega,
    and Nike, and a number of foreign facilities. This data along with
    data from the NIF will provide the scientific basis for the targets
    needed for IFE.

In 1990 the Fusion Policy Advisory Committee recommended that inertial
fusion energy (IFE) and magnetic fusion energy (MFE) be developed in
parallel. The Fusion Energy Sciences Advisory Committee, following the
1999 Snowmass Workshop, reaffirmed this policy and recommended funding
levels for both approaches. Similar recommendations were made by the
Secretary of Energy Advisory Board in 1999.

**III. Approaches to Inertial Fusion Energy**

There are many different types of targets, several types of chambers,
and several types of drivers and systems to deliver the driver energy to
the target. To some extent these systems or components are independent
so there are many possible combinations. This independence allows
modular, cost-effective research on key issues with synergy among the
integrated concepts. However the various combinations of drivers,
targets, and chambers must work together in a power plant, and not all
combinations are equally compatible or self-consistent. Consequently
each of the three main approaches puts most of its effort into the
combination that currently appears to be most attractive from a physics,
engineering, and economic perspective. These are listed in the following
table:

**Table I: Main Approaches to Inertial Fusion Energy**

+-------------------------------+--------------+----------------------+
| **Driver**                    | **Target**   | **Chamber**          |
+-------------------------------+--------------+----------------------+
| Lasers-                       | Direct Drive | Dry Wall             |
|                               |              |                      |
| Krypton Fluoride (KrF), or    |              |                      |
|                               |              |                      |
| Diode Pumped Solid State      |              |                      |
| (DPPSL)                       |              |                      |
+-------------------------------+--------------+----------------------+
| Heavy Ion Beams               | Indirect     | Thick Liquid Wall    |
|                               | Drive        |                      |
+-------------------------------+--------------+----------------------+
| Z-pinches (X-rays)            | Indirect     | Thick Liquid Wall    |
|                               | Drive        |                      |
+-------------------------------+--------------+----------------------+

The drivers are expected to be the single most expensive part of the
power plant. There are substantial research programs in heavy ion
accelerators, krypton fluoride lasers (KrF), and diode pumped solid
state lasers (DPSSLs). The heavy ion fusion program is currently funded
through the Office of Fusion Energy Sciences (OFES) and the laser
programs are funded through NNSA as a result of Congressional
initiatives. There is a small concept exploration programs on z-pinches,
which builds on the large z-pinch program supported by the NNSA for
defense purposes.

In all IFE targets the fusion fuel is compressed before it is ignited.
There are two broad methods of compression and two methods of ignition.
The fuel is compressed either through an implosion driven directly by
the driver beams (direct drive) or by converting the driver energy to x
rays that then drive the implosion (indirect drive). The two classes of
ignition are hot-spot ignition and fast ignition.

In hot-spot ignition, the implosion both compresses and heats a hot spot
in the center of the fuel. This spot ignites and subsequently burns the
rest of the fuel. These target designs are the most mature.

In fast ignition, the target is compressed by one driver, and a spark is
ignited by a separate, very high intensity source such as a short pulse
laser. Fast Ignition could be used with any of the main driver concepts.
There is broad international interest in fast ignition because it could
lead to higher fusion gain with a smaller driver. But it is a less well
developed approach, and there are important technical uncertainties.

Chambers also fall into a number of general types. They are classed by
how the first wall of the chamber is exposed to the blast from the
target. The types currently receiving the most attention are dry-wall
chambers and thick liquid wall chambers. The dry wall chambers are the
simplest, and would be constructed of advanced materials that can last
for an acceptable fraction of the plant life. These chambers may contain
some gas to protect the wall from x-rays, charged particles, and target
debris. In thick liquid wall chambers, a layer of flowing molten
material is used to protect the wall from neutrons as well as from
x-rays, charged particles, and target debris. If successful, liquid wall
chambers can greatly reduce the materials development challenges posed
by fusion energy.

It should be pointed out that in all of these approaches, great
attention is being paid to the issue of radioactive waste. Chambers,
blankets, coolants, and targets, are all being designed to minimize
radioactive waste. Systems can be designed which would produce little,
if any, high-level waste but the decision of whether to pursue designs
which would generate small quantities of high-level waste versus larger
quantities of low-level waste must be made in the context of economics,
regulatory constraints, and public perception. A substantial development
effort will be required before the required materials will be available

The various combinations in Table I may change as the research evolves.

**IV. The Proposed Inertial Fusion Energy Roadmap**

The IFE Development plan shown below will address the challenges put
forth in the Section V. The plan has three phases preceding a
demonstration power plant. The IFE community has developed specific
milestones that must be met at each level before a concept is ready to
advance to the next step.

**Phase I**: The first phase is focused on determining the scientific
validity and developing the underlying technology for each concept. This
phase is sometimes referred to as "concept exploration" and "proof of
principle." There are research programs in all areas, including target
physics, target fabrication and injection, fusion chambers, and driver
physics and technology. The target physics program includes research on
the fast ignition approach as well as the main line direct and indirect
drive central hot spot ignition approaches. The two laser driver
facilities for Phase I, the Electra krypton fluoride (KrF) laser and the
Mercury diode pumped solid-state laser (DPSSL), are under construction
and making excellent progress. The Phase I facility for heavy ion
fusion, the Integrated Beam Experiment (IBX), has been designed but not
yet been approved. The z-pinch driven approach is currently being
studied but does not yet have official Department of Energy funding.
Collaborative research on fast ignition is being carried out largely on
facilities in Europe and Japan. However, because of the widespread
applicability of short pulse lasers for NNSA missions, the technology
for fast ignition is being funded in NNSA through Congressional
initiative. There is also a small US research activity, funded by the
Office of Fusion Energy Scicnce, that heavily leverages both the NNSA
and the European and Japanese efforts.

**Phase II:** Phase II will bring together the key components to ensure
they can work together with the required efficiency, repetition rate and
precision. These facilities will have both full scale and subscale
components, as needed for technical validation. Included will be
development of low cost, mass produced targets, as well as critical
chamber issues. The IFE community refers to these facilities as
"Integrated Research Experiments" or IREs. They are the next major steps
in inertial fusion. The IRE facilities are expected to be substantially
less expensive than either the magnetic burning plasma experiment or the
NIF. During Phase II it is expected that the NIF will start providing
needed data on burning IFE plasmas on a single-shot basis. However, the
NIF glass laser technology cannot operate at high repetition rates and
does not have the efficiency or the durability needed for commercial
power production. The NIF fusion chamber is not designed to manage the
fusion power that would be generated in a fusion power plant. It is the
combination of the NIF target physics plus the IRE driver and other
power plant technologies which will provide the fundamental basis for a
fusion power plant.

**Phase III:** The Engineering Test Facility (ETF) will provide the
first demonstration of repetitive fusion power. The ETF will operate at
a fusion power level of 200 to 1000 MW, and would have the capability of
generating a net electrical power output of between 100 and 300 MW. The
ETF will provide a test bed for demonstration of all of the IFE plant
systems, including tritium breeding and recovery, power conversion,
materials testing and component development. It would also have
operational flexibility. It could run in burst mode tests at high yield
and full rep-rate to demonstrate high gain targets and to study chamber
response to high yield target emissions. Long-term testing could be done
at lower yield and/or rep-rate in order to keep the heat transfer and
conversion costs lower. The exact specifications of the ETF must await
the R&D that will take place in Phases I and II. Information from the
ETF will be used to design a full-scale IFE demonstration power plant
(Demo). It may even be possible to use the ETF driver with new
full-scale chamber and plant components in a fusion power Demo.

![](media/image1.png){width="6.5in" height="4.875in"}

**Figure 1: The IFE Development Path plan proceeds in 3 phases to an
Engineering Test Facility (ETF) that would be capable of putting
electricity on the grid from inertial fusion**

**Program Highlights**

The realization of Inertial Fusion Energy requires two key ingredients:
the capability to ignite fusion fuel and release more energy than was
invested, and the capability to reliably repeat this process at high
repetition rates while extracting useful energy. There has been major
technical progress in both areas in the past few years.

**Fusion Ignition**

Both NNSA and international research have made major progress toward the
goal of achieving fusion ignition. In the United States, the Advanced
Strategic Computing Initiative in NNSA has improved the computational
tools and increased the computing power, used to design and predict the
performance of inertial fusion targets. Target designs for the National
Ignition Facility (NIF) have improved in both robustness and predicted
yield. As shown below, the NIF experimental program will begin soon
after first light with the first 4 beams (a quad), which is currently
expected toward the end of FY03. As more beams are added, increasingly
complex target experiments will be possible. By the end of FY07, it will
be possible to begin high quality symmetry experiments in support of
ignition. The full capability of NIF for ignition experiments will be
available at the end of FY08. NIF will be capable of testing a variety
of ignition target approaches. NIF will initially be configured for
indirect drive, and can be configured for direct drive. With the
development of new technology, it could also be configured for fast
ignition. In addition to NIF, over the next decade, critical physics
data for ignition physics including fast ignnition will be provided by
Omega and Z as well as international facilities.

![](media/image2.png){width="6.496527777777778in"
height="4.336805555555555in"}

Figure 2: The National Ignition Facility (NIF) will begin experiments
with 4 beams in FY2003 with full scale ignition experiments to start in
FY09

**Progress in Laser Fusion Energy:**

Since 1999, the funding for the Laser IFE approach has been
approximately equal to the FESAC recommendations. An integrated program
has been fielded that deals with laser, target fabrication, optics, and
chamber issues. Both the KrF and DPPSL lasers have made impressive
progress in durability, efficiency, and technology. KrF lasers have made
important progress in the electron beam diode, pulsed power and in
simulation tools, and the DPSSLs have made important progress in
manufacturing the needed crystal laser media, the diode power source and
the gas cooled amplifier heads. Directly driven laser targets have also
made substantial progress. Three years ago there were serious doubts
about the hydrodynamic stability of these targets, but recent
calculations indicate that the instability may be substantially reduced
by shock heating of the ablator using an appropriate pulse shape. In
addition, experiments on Nike have shown that a thin high-Z layer can
reduce laser imprint that seeds instability. Studies show that a laser
fusion target can be mass produced for less than \$0.16 each, which is
well within the economic requirements from power plant studies. There
has also been rapid progress in understanding the basic science of
dry-wall chambers, target injections systems, and final optics
protection for the laser option. Dry wall chambers have the highest
degree of commonality with MFE fusion technology. These chambers can
benefit directly from much of the fusion materials development described
in the MFE development plan.

The major challenges for the Laser IFE approach are:

1.  KrF laser efficiency, lifetime, and reliability

2.  DPPSL laser cost and beam quality

3.  Target fabrication and Injection

4.  Development of first wall materials/protection schemes for the
    fusion chamber

5.  Durability of final optics

**Progress in Heavy Ion Fusion (HIF) Energy**

In contrast to lasers, the heavy ion driver program has received
substantially less funding than recommended three years ago. The program
has dropped almost all accelerator technology development and is
concentrating on basic beam science in injectors, transport, and
focusing. Three new, modest-scale science experiments have recently
begun operations. These three experiments study, separately, the most
important issues for accelerator beam dynamics. They include the new
Injector Test Stand, designed to study innovative ion sources and
multiple beamlet merging; the High Current Experiment, which addresses
issues of high current beam transport in the accelerator; and the
Neutralized Transport Experiment, which reproduces the phenomena that
control beam focusing in HIF chambers. Fully integrated target design
calculations are now available with the required gain for energy
production, and self consistency with current predictions for driver
focusing performance. Separate efforts are addressing HIF chamber and
target technologies and integrated system modeling. Scaled hydraulics
experiments have identified nozzle designs that can create all of the
liquid jets configurations required for thick liquid chambers, including
innovative vortex nozzles that can coat the insides of driver beam tubes
with thick liquid layers. For heavy-ion fusion there is now a
chamber/target/driver point design where the final focus magnets and
chamber structures all have predicted life times exceeding 30 years. The
next step in heavy ion drivers is called the Integrated Beam Experiment
(IBX). The IBX is part of Phase I of the development and precedes the
Integrated Research Experiment. The IBX would integrate key physics
issues at moderate beam current and beam energy in an integrated
facility, including injection, acceleration, drift compression, and
final focus to a small spot in a target chamber. Focusing intense beams
in the fusion environment remains the most important issue.

The major challenges for the Heavy Ion approach are:

1.  Focal spot size under fusion chamber relevant conditions

2.  Accelerator cost

3.  Target fabrication

4.  Demonstration of liquid protection chambers and target material
    recovery

5.  Focus magnet lifetime

**Progress in Z-Pinch Fusion Energy**

Presently, this work is at the Concept Exploration level and is not
directly funded by DOE. There is substantial interest in z-pinches, and
a US-Russia collaboration on Z-Pinch IFE is being formed.

Excellent progress has been made on z-pinch driven capsule compression
experiments on the Z machine at Sandia National Laboratory. High yield
target calculations predict yields for z-pinch driven IFE capsules in
the range of 0.5-3 GJ. Z-pinch driver development is proceeding from Z
(18 MA of current) to an upgraded machine called ZR (26 MA of current),
which will be within a factor of 2-3 in current (4-9 in energy)of the
level predicted for high yield. A Recyclable Transmission Line (RTL)
concept for rep-rated power plant operation is being developed. RTL
experiments on Saturn (10 MA of current) have demonstrated the required
RTL electrical properties, and a first z-pinch power plant study has
produced a scenario for RTL operation. LTD (Linear Transformer Driver)
technology will be developed for the rep-rated pulsed power. The next
steps in z-pinch IFE development includes further experiments on RTL's,
rep-rated pulsed power, and fusion chamber experiments on
shock/containment.

The major challenges for the Z-pinch approach are:

1.  RTL structural integrity and cumulative amount and recovery of RTL
    mass as well as manufacturing economical RTL's

2.  Activation of the RTL material

3.  Blast mitigation effects for the first wall of the fusion chamber

4.  Development of rep-rated pulsed power

5.  Further development and optimization of the physics basis of z-pinch
    targets

**Progress in Fast Ignition**

There is a broad international interest in fast ignition and increased
interest by NNSA in producing the driver technology. Recent target
experiments have been encouraging, particularly those on the Gekko XII
laser in Japan which demonstrated both compression and substantial
heating with a short pulse "ignitor" beam at small scale. The potential
advantages of fast ignition, higher gain at lower driver energy,
compatibility with all driver options, flexibility in chamber and
illumination systems and reduced target fabrication precision, motivate
continued research. But the laser-target interaction is more complex
(and less understood) than the other approaches and an integrated model
(through burn) of the physics is needed.

The major challenges for fast ignition are:

1.  Further development of the target physics at ultra-high intensity
    (10^20^ W/cm^2^)

2.  Development of a long lifetime final focus system compatible with a
    fusion chamber

3.  Development of efficient short pulse technology capable of the pulse
    rates and durability required for IFE.

4.  Timing and placement of the ignition laser on the compressed target

5.  Fabrication of fast ignition targets if special features like a
    "cone focus" are required.

# Objectives and Metrics for Development Phases

Each of the approaches being considered for IFE is at a different stage
of development and will progress through these phases at a different
time and rate that depends on both funding and success in meeting the
R&D objectives. Some common, top-level metrics needed to proceed to the
next development phase (adapted from the 1999 FESAC Knoxville Panel on
OFES Program Balance and Priorities meeting) are summarized in the Table
II below. In addition to these generic milestones, each approach has
specific issues to address and objectives to meet at each phase.

+-----------------------------------------------------------------------+
| ## Requirements to Qualify an IRE                                     |
|                                                                       |
| -   Resolve key proof-of-principle driver issues (efficiency,         |
|     reliability, focusability, cost) that are specific to each        |
|     approach.                                                         |
|                                                                       |
| -   Adequate gain IFE target designs with 2-D hydrostability for      |
|     plausible beam non-uniformities.                                  |
|                                                                       |
| -   Plausible pathways for target fabrication and injection.          |
|                                                                       |
| -   A chamber design concept that is self-consistent with target      |
|     illumination geometry, final focus and beam propagation, chamber  |
|     clearing, and adequate lifetime.                                  |
+-----------------------------------------------------------------------+
| ## Requirements to Qualify an ETF                                     |
|                                                                       |
| -   Adequate target physics data from NIF and other ICF facilities on |
|     implosion symmetry and capsule/fuel layer smoothness.             |
|                                                                       |
| -   High confidence 3D calculations for IFE targets, validated with   |
|     data from NIF and other facilities                                |
|                                                                       |
| -   IRE-level confirmation of scaling for ETF driver cost, lifetime   |
|     at rep-rate, and adequate efficiency.                             |
|                                                                       |
| -   Test injection of prototype ETF targets in simulated fusion       |
|     chamber environment (could be separate facility).                 |
|                                                                       |
| -   Demonstration of techniques to mass produce low cost IFE targets. |
|                                                                       |
| -   Final focus lifetime data for sufficient number of shots under    |
|     ETF prototypical conditions.                                      |
|                                                                       |
| -   Experiments that resolve issues of beams driving ETF targets      |
|     (e.g., beam balance, symmetry, imprint, filamentation, chamber    |
|     plasma/gas interaction)                                           |
|                                                                       |
| -   Experimentally validated chamber models that show acceptable      |
|     clearing times; evidence of acceptable chamber materials          |
|     reliability, coolant chemistry control, and tritium control and   |
|     recovery.                                                         |
+-----------------------------------------------------------------------+

# Table 2. Requirements to Proceed to IRE and ETF Development Phases

**Summary**

We have presented a plan to develop Inertial Fusion Energy. Energy has
risen in visibility with the development of the President's National
Energy Policy, as well as with Energy Bills passed in both houses of
Congress. All three documents call attention to fusion's potential: The
fuel for fusion is abundantly available to all nations for thousands of
years, the fusion process is intrinsically safe, and the waste from
properly designed fusion chambers would be relatively short-lived.
Fusion power plants could be the source of hydrogen for a fuel cell
based transportation system that is not dependent on oil. Climate change
has also received considerable public attention, and the predicted
timescale for accumulation of CO2 in the atmosphere suggests that
attractive clean energy sources such as fusion should be developed
aggressively in the next few decades. These factors, plus the
significant technical progress in this field, warrants a broad based
effort to accelerate the development of fusion energy . For IFE this
will require adequate resources and a management structure in the
Department of Energy which has development of IFE as a primary
objective.