**Thoughts on Fusion Energy Development**

**On the Occasion of the Fusion Power Associates Annual Meeting and
Symposium,**

**3-4 December 2008**

**R. F. Post**

First off, I wish to thank Steve Dean and his Fusion Power Associates
for honoring John Nuckolls and me, and for giving us this opportunity to
comment on a field or research that has been our passion for decades. In
my case, I would also like to thank Ken Fowler for proposing the theme
of the symposium to Steve Dean many months ago and then diligently
following through on its details..

In what I have to say I will be talking about paths to fusion and about
fusion's history as I recall it. Not about the negative aspects of
history, as in "those who forget history are doomed to repeat it," but
the positive view that: "If we remember that in the past we had a
clearer vision of the path to fusion, and if we have gotten off that
path, we know that the path exists and that we can find it again if we
try."

Where to begin? - And what to highlight about the six-decades-long love
affair that I have had with fusion research? My fascination with fusion
really began early in 1952 as a result of three classified lectures
given by Herb York I was then a year out of graduate school and working
at the Radiation Laboratory (now LBL). Herb's series of lectures covered
the physics issues of controlled thermonuclear reactions (CTR) and
described the U. S. fusion programs at Princeton University, headed by
Lyman Spitzer, and at Los Alamos, headed by Jim Tuck. Both groups were
working on versions of the only game in town at that time -- trying to
use specially shaped magnetic fields to stably contain a 100
million-degree-hot ionized gas - plasma -- composed of electrons and
fusion fuel nuclei -- heavy hydrogen isotopes

For the benefit of the non-scientists, getting power from a magnetically
confined fusion plasma is the nuclear equivalent of burning natural gas
in a furnace -- except that here the furnace liner is to be made up of
non-material magnetic field lines. The other main present approach to
fusion - using lasers to heat a tiny pellet of fusion fuel to ignition -
did not exist. The laser had not yet been invented and John Nuckoll's
pioneering work in the area of laser-based fusion research was yet to
come.

Herb York's lectures on magnetic fusion had a specific goal in mind --
to stimulate the interest of us physicists to join him in forming a new
laboratory on a site near Livermore. This new lab was to have fusion
research as one of its main goals.

To make a long story short, after Herb's lectures there was ferment
among many of us - trying to think of ways to solve the controlled
fusion problem. Several of us then joined the new lab, some to work on
controlled fusion and others to work on classified military
applications.

At this point I think it is important to make clear the underlying
source of our fascination with fusion research -- then and now. Even
before 1952 it was beginning to be evident that within perhaps less than
a century the world could no longer count on fossil fuels for its
ever-increasing energy demands, In long term it would have to rely on
energy released in nuclear reactions, that is, either fission or fusion.
To those of us that went to Livermore with Herb it seemed obvious that
the fusion of heavy hydrogen was the way to go, and we pointed to the
world's huge fusion fuel reserve - the fact that 1 in every 6500 atoms
of hydrogen in water was a deuterium atom. Here was a fuel reserve that
was not only virtually inexhaustible, but one that would be cheap and
universally available; no fusion OPECs and no future conflicts born of
competition for limited fuel resources.

To emphasize the significance of fusion's fuel reserves, here is a
thought experiment: Think about the amount of ordinary water -- H2O -
that would flow through a city water main about a foot and half in
diameter at normal pressures . Then think about putting that flow of
water into a deuterium separation plant, using well-known
energy-efficient separation techniques. From that input of ordinary
water there would come out of the separation plant a small stream of
heavy hydrogen - deuterium, This deuterium, if distributed to fusion
power plants and fused to completion, would represent a fuel energy
input rate equal to the entire world's energy input rate today --all the
oil and natural gas wells, all the coal mines, all the hydroelectric
plants -- everything! And as to inexhaustibility, how long do you think
it would take to pump all the water in the oceans through an 18-inch
water main?

A bit more fusion history: Serious effort on magnetic fusion research
began in about 1950 in classified research programs in the U. K., the U.
S. and the Soviet Union. By 1955 it was apparent that magnetic
confinement of a hot plasma was a much more complex process than first
thought, so that at the 1958 Geneva "Atoms for Peace" Conference, these
three countries declassified and described all of their fusion research
results in order that the fusion quest could be pursued by all the
nations.

To achieve net fusion power it is necessary to heat and then to confine
a fusion plasma long enough for the fusion energy released to exceed the
energy required to heat the fuel to fusion temperatures. However, as of
Geneva 1958 it was clear that the plasmas in every magnetic
configuration that had been tried exhibited plasma instability and
turbulence, leading to unacceptably rapid loss of the plasma. This
universal observation -- of the negative effects of turbulence on
magnetic confinement - defined the central problem for magnetic fusion
research from that day forward, up to and including today.

First, some basics of the magnetic confinement for the non-scientists:
Strong magnetic fields change the straight-line orbits of the ions and
electrons of a plasma into tight spirals moving along the field lines.
This inhibits escape of the particles across the field lines, but unless
something is done about it, does not restrict their motion along the
field lines. In magnetic fusion research, the choice of what that
"something" should be has from its beginning separated magnetic fusion
researchers into two distinct groups-- those solving the "problem of the
ends" by using "closed-field" systems - field lines chasing their tails
inside a doughnut-shaped chamber , or those studying "open-field'
systems, that is, using a tube-shaped bundle of field lines and then
"plugging" the end leaks by strengthening the field at the ends to form
"magnetic mirrors." But the plasma physics issues introduced by making
one or the other of these choices are profoundly different, and (here
comes the personal bias) the choice that was actually made, in the late
1980s, by most of the world's fusion programs - to restrict their
research to closed-field systems - has severely slowed our progress
toward the fusion goal.

Up to the mid-1980s the world's magnetic fusion energy program was on
the right path. The program was a broadly based one, with sizeable
experiments investigating a variety of both closed and open systems,
backed up by an extensive theoretical and computational effort. But, not
surprisingly, the criterion that was adopted by the policy makers at
that time for judging the merit of one approach over another was how
close the magic fusion numbers -- plasma confinement time, plasma
density, and plasma temperature - that had been achieved experimentally
came to the numbers required for net fusion power. By the middle 1980s
one closed-field system -- the tokamak - was the clear winner by this
criterion. Why? Because early on, starting with experiments by its
Russian inventors, it was found that all you needed to do to get better
numbers out of a tokamak was to build a bigger one. Though the tokamak
was very difficult to analyze theoretically, and was clearly plagued by
a variety of plasma instabilities, nevertheless when one plotted the
confinement times of succeeding generations of ever-larger tokamaks
against the square of their plasma radius the data lay on an
upward-sloping straight line -- aiming directly at plasma fusion
ignition in some future, necessarily very large, tokamak.

As I see fusion's history, this simple curve sounded the death knell for
all approaches that did not resemble or support the tokamak in some way
-- specifically. it virtually terminated the study of open-ended,
systems, apart from some pockets of resistance at Tsukuba in Japan and
at Novosibirsk in Russia. This shift in program breadth happened even
though great progress had been made in open-ended mirror systems
following the invention of the tandem mirror in 1976 by Ken Fowler and
Grant Logan, here at the Laboratory, simultaneously with its invention
in Novosibirsk, Russia, by Dimov. In that heyday for mirror research a
large tandem mirror experiment here at Livermore, TMX, was proposed and
construction was completed in 18 months. Tandem mirror systems were also
built with similar speed - at MIT and the University of Wisconsin in the
US, and at Tsukuba in Japan. At Livermore TMX was followed by an upgrade
-- TMXU, and then by the construction of a really large tandem mirror,
MFTX. Days after its completion and first shakedown tests MFTX was
mothballed and all mirror-based work in the U. S. was terminated.

Where are we in magnetic fusion research today? We are partway down a
long trail that dates back to 1985, when a proposal for a really large,
internationally sponsored, tokamak -- ITER - was made. It then took 20
years -- until 2006 - before funding agreements (10 billion dollars) and
a site was chosen by the international partners. Another 10 years will
be required for construction and 20 years of operation are planned,
after which a "demo" tokamak, one actually generating electricity would
be considered (since the ITER experiment will generate only heat).

To wrap up (here comes the personal bias): Can we afford to wait that
long for fusion? Are there a faster, better, ways to get there? Here
I'll be discussing magnetic fusion only. I'll not talk about the
impressive progress in laser-based fusion towards fusion ignition. --Ed
Moses and his co-workers will certainly be covering that in their talks.

First, about ITER: I give ITER high marks for keeping magnetic fusion
from dying on the vine, for the international cooperation it has
fostered, and for the fusion-related science and technology that was
developed and is being developed to implement it. But ITER is like the
TV ads for a new wonder drug: "If you are patient this drug will do
wonders, but -- look out for those side effects!" The "side-effects" of
ITER, in my opinion, have been catastrophic for magnetic fusion
research. They include: (1) narrowing a program that cries out for
breadth to insure success, (2) turning away bright young researchers
from magnetic fusion research because its course is already a "done
deal," and (3) drying up funding for anything that does not support or
at least resemble a tokamak.

Enough of negativity! I would like very much to finish this talk on a
positive note. First, our critical need for clean and sustainable
sources of energy represents a real opportunity for fusion research if
we take advantage of it. One way to put the situation today is to talk
of it in terms of "present reality" and "future reality." "Present
reality" says: "In the present economic climate and with our prior
commitments there is no way we can support a new effort." The prime
example of "future reality" was when John F. Kennedy said "we are going
are going to put a man on the moon in ten years." He knew that the
science and rocket technology needed for a moon landing was there, along
with the money to pay for it. I believe that we are in a similar
situation today with respect to the magnetic approach to fusion power.
We have the basic scientific understanding, the computational
horsepower, and the technology to take a new, broader, look at the
problem. And we certainly have the financial wherewithal. For example,
we are spending 700 billion dollars a year to import oil. One week of
that rate of expenditure -- 11 billion dollars - is equal to the entire
U S. magnetic fusion funding over its 56 plus years of existence. A
4/10^th^ percent tax on that oil could pay for a fusion budget that is a
factor of ten larger than the present budget.

Are there better, faster-to-develop, approaches to magnetic fusion than
the tokamak? Yes, there are! As an example, I would cite the recent
findings of a DOE-sponsored committee that is taking a new look at
open-ended systems -- in particular at new forms of the tandem mirror
that we call "ATMs" (for "Axisymmetric Tandem Mirror" -- not for
machines for getting money -- yet). The committee is chaired by a former
Lab employee and mirror group leader Tom Simonen (who is doing a great
job). Its members include several Lab employees and retirees, plus
researchers from other labs, including MIT, Princeton, the University of
Texas, and Los Alamos. We are now writing the final report. It concludes
that the open-ended ATM represents a simpler and easier-to-engineer,
approach to magnetic fusion than ITER, since it is modular in nature
and, being axisymmetric, it employs only simple circular coils to create
its confining magnetic fields.

What is even more important is that we believe that the ATM could be
free of the plasma turbulence that haunts the tokamak and that dictates
its huge size. In support of this possibility is a plasma stabilization
concept analyzed theoretically by Lab physicist Dmitri Ryutov (when he
was at Novosibirsk in the 1980s). His theory has been confirmed in
detail by a series of experiments in the Gas Dynamic Trap axisymmetric
mirror machine at Novosibirsk. In the GDT a hot, dense, plasma is
confined stably for times in agreement with theoretical predictions, and
the plasma shows no evidence of turbulence.

Do I think that the ATM could be a "future reality"? Yes I do! Do I
think that it is the only worthwhile new approach to magnetic fusion?
Definitely Not! Do I think this country should rapidly re-invigorate its
magnetic fusion program? You bet I do!