VOL. 5, NO. 1 • SPRING 2001

Big Displays Come to Life

on High-resolution Wall

At the High-resolution Wall are, from left, Scott Klasky, Steve Jardin, Irving Zatz, and Doug McCune. The image displayed

on the wall is of National Spherical Torus Experiment magnetic field lines.

Photo by Elle Starkman

During the past year, the High-resolution Wall, also

known as the Visualization Wall, began operating

at the U.S. Department of Energy’s Princeton Plasma

Physics Laboratory (PPPL). The wall has a resolution

quality more than three and a half times better than highdefinition TV. Ten clustered computers work together

and nine projectors beam pixelated images onto this large

display wall, resulting in superior clarity. The PPPL

project originated as a result of a conversation between

Continued on page 2
PPPL NEWS • Spring 2001 Page 2

The PPPL NEWS is issued by the Princeton Plasma Physics Laboratory, a research facility supported by

the United States Department of Energy and managed by Princeton University. Correspondence and

requests to reprint material should be directed to: Information Services, Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543; telephone 609-243-2750; fax 609-243-2751; e-mail pppl_info@pppl.gov

.

PPPL NEWS

Information Services Head: Anthony R. DeMeo

Editor/Writer: Patti Wieser

Photographer: Elle Starkman

Layout and Graphics: Gregory J. Czechowicz

and Patti Wieser

Professor Kai Li from the Princeton University Computer

Science Department and PPPL Chief Scientist Bill Tang.

Professor Li’s Display Wall on main campus was the

model for PPPL’s effort. PPPL’s Scott Klasky is the

Wall

Continued from page 1

driving force behind the assembly of the High-resolution

Wall and it’s ongoing improvements, and Irving Zatz of

PPPL’s Engineering and Technical Infrastructure Department, has been a valuable collaborator in the continuing improvement of the facility. Overseeing the project

are PPPL’s Steve Jardin and Doug McCune. Below,

Jardin answers questions about the wall.

What is the main purpose for the construction of the

PPPL High-resolution Wall?

The main purpose of the Wall is to provide a very

powerful, high-resolution, scalable display so that our

theoretical researchers can see the fine-scale structure in

their output from big supercomputers. The computers we

use, particularly at NERSC (the National Energy Research Supercomputer Center at Berkeley) keep getting

faster and more powerful, but desktop monitors have not

been keeping pace in terms of their resolution capability.

One way of seeing this is in terms of parallelism. The way

big supercomputers are getting faster now is that they

combine many (up to 4,000 or more) “standard” computers and operate them in parallel. We call that MPP, or

massively parallel processing. The display wall is an

initial attempt to make a high-resolution display by combining nine “standard” displays in parallel. Its scalability

means that even higher resolutions can be readily achieved

with the addition of more processors and projectors.

How common is this type of facility at the National Labs?

PPPL is the first U.S. fusion facility to have such a wall,

but others are now following. There are several of these

walls at the big national laboratories and in computer

science departments.

In layperson’s terms, what are some of the “gee whiz”

statistics pertaining to the assembly of the wall and its

operation?

The High-resolution Wall is basically nine standard displays tiled together to make one display with higher

resolution. Each of the nine displays has a resolution of

about 800 x 1,000 pixels. Thus, the tiled wall has a

resolution of about 2,400 x 3,000 pixels or 7.2 million

pixels. The highest resolution digital TV formats that are

coming out have about 2 million pixels for comparison.

The system has nine projectors and one computer to drive

each screen, plus a control computer to give directions to

the others. It is clearly the Lab’s fastest device for displaying visualization. When the computers are not being used

to drive the screen, our researchers can use them in

parallel to perform modest-scale scientific calculations.

What are some of the most interesting applications that

have been tried at PPPL? What is the routine use (if any)

of the wall?

We were somewhat surprised by how much people like to

use the wall for making presentations. We have had many

meetings held there where most of the presentations did

not really need the high resolution that the wall provides,

but people like the size and crispness of the display. Also,

presenters have found that they can include much more

information on their slides without it appearing “too

busy” because there is so much room to work with.

Q&A
Page 3 PPPL NEWS • Spring 2001

We find that more and more, our research groups of six to

12 people are holding working meetings in the Highresolution Wall room and using the wall to show each

other the results of their calculations. It is much better

than everyone gathering around someone’s desktop display, and it does not involve making hard-copy viewgraphs.

Also, we are using the wall much more now to view

movies of our simulation data. We find that we are

noticing details in our simulation data that were not

previously apparent.

What are the plans for the visualization facility at PPPL

in the near term and the longer term?

We are now preparing proposals in several related areas.

One area is that of “virtual meetings” with other laboratories. By using the wall, a collection of cameras, and

some microphones and speakers, we can make an excellent virtual meeting room where a group here can see and

talk with a group at a similar facility at another laboratory.

The size and resolution of the wall make this a much more

attractive setup than our present videoconference facilities. Also, we have a proposal to make a similar facility in

the NSTX Control Room to show many plasma displays

simultaneously at a size in which everyone in the control

room can see them.

These two ideas can be combined to have remote control

rooms for collaborators where they can see and interact

with everyone and view all the data. Presently, projects

are underway to develop an automatic alignment system

for the projectors and to create a portable and scalable

wall that can be moved from place to place.

What about the farther out possibilities, e.g., virtual

reality?

Things are really moving in that direction. It is just a

matter of when and how much it will cost. We are only a

few years away from having the capability to create a 3-D

real-time virtual walkthrough of an operating device such

as NSTX. I think that in five to 10 years we will have

collaboration displays that take up two or more walls in a

room, and the displays and audio will be so sharp that it

will be just like being in the same room as the people you

are remote conferencing with.

As for the virtual reality, it is almost here. Some of our

Japanese collaborators already have rudimentary virtual

reality displays that use four walls and a ceiling. I think the

real push will come when someone uses such a display to

discover something really new that they couldn’t visualize without it. Then it will really take off everywhere. It

helps that the home game market is so strong, as that is

providing a commercial incentive for companies to keep

improving the display components and is driving the

costs down. ●

Proposed Compact Stellarator Reviewed

PPPL’s Michael Zarnstorff (standing, left) and Jeffrey Freidberg of

the Massachusetts Institute of Technology (standing, right) discuss

the proposed National Compact Stellarator Experiment (NCSX)

during a recent NCSX Physics Validation Review meeting at PPPL.

The Physics Validation Review of the proposed

National Compact Stellarator Experiment (NCSX)

was held in March at PPPL.

The 13-member peer review committee addressed a

Department of Energy charge that had several elements,

including scientific merit, soundness of the NCSX physics basis, and relevance to fusion program goals. Committee members were also asked whether the level of experimental flexibility and robustness satisfies the Fusion

Energy Science Advisory Committee (FESAC) requirements for the compact stellarator to attain proof-ofprinciple status. The review committee gave a strong

affirmation on these questions and commended the

preconceptual engineering design concept. Professor

Gerald Navratil of Columbia University served as the

Scientific Chair of the review.

Prior to the meeting, the project team prepared a

document “NCSX Physics Validation Report” to assist in

the review process. This report documents the motivation

and goals for NCSX, its physics and engineering design

characteristics, its physics basis, and plans. It is posted on

the NCSX web site at http://www.pppl.gov/ncsx. ●
PPPL NEWS • Spring 2001 Page 4

Liquid Lithium Experiments are

Underway on CDX-U Machine

By Anthony DeMeo

At the Current Drive Experiment-Upgrade are Dick Majeski (left)

and Bob Kaita, who co-head the project.

Among the greatest technological challenges in the

creation of a practical fusion power reactor is the

development of the so-called “first wall.” This is the

material surface surrounding the hot fusion plasma, which

physicists estimate will be subject to power densities in

excess of 25 million watts per square meter from fusion

neutrons, escaping plasma particles, and radiation. Present

designs call for a lithium

blanket behind the first wall.

Fusion neutrons will react

with the lithium to produce

tritium that would be extracted and used as fusion

fuel. These neutrons will also

react with the materials in

the first wall itself, producing radioactive isotopes (activation) and causing chemical changes that may lead to

its erosion and loss of structural integrity.

Experiments now in

progress on the Current Drive

Experiment-Upgrade (CDXU) may eventually yield a

revolutionary solution to this

materials problem and, of

equal importance, may demonstrate techniques for improved plasma performance in

the near term. The work, performed in collaboration with

the University of California, San Diego; Oak Ridge

National Laboratory; Sandia National Laboratories; and

others, involves studies of the interactions between plasma

and liquid lithium. A liquid first wall would not be subject

to the kind of damage a solid wall can experience, and

would be able to handle higher heat loads. While present

experiments are focusing on the near-term physics advantages, physicists envision the use of flowing liquid lithium

as the first wall in a fusion power reactor.

Bob Kaita, who is leading the effort on CDX-U with

Dick Majeski, noted that “the use of a flowing liquid

lithium wall can potentially eliminate the erosion problem because the wall is continuously renewed. Furthermore, it may result in a substantial reduction of activation

because neutrons will no longer react with materials that

stay fixed in a solid first-wall structure.” Kaita went on to

point out that lithium can withstand the onslaught of 25

million watts of power per square meter, and it may be

able to soak up the helium that is produced in the deuterium-tritium fusion reactions, which must be removed

from the plasma.

As remarkable as these potential benefits seem, they

are not the end of the story.

Significant physics advantages may also accrue, including control of the plasma

oscillations and “kinks”—

instabilities that can destroy

plasma confinement. Experiments on the former Princeton Beta Experiment-Modification at PPPL and other

tokamaks demonstrated that

a conducting wall inhibits

these plasma instabilities.

Liquid lithium could also

serve as a conducting wall,

and if the lithium flows at

rates of 10 to 20 meters per

second, its ability to stabilize the plasma may actually

improve.

Limiters are metal surfaces that are specially designed to protrude from the

vacuum vessel wall toward the edge of the plasma. Their

job is to prevent the plasma from striking the vacuum

chamber and sputtering impurities, especially heavy metals, into the plasma. Metal atoms soak up energy and

radiate it away, causing the plasma temperature to drop.

In principle, plasma particles (deuterium ions) striking the limiter plates are neutralized and return to the

plasma where they again become ionized. This recycling

tends to cool the plasma edge, and it limits the ability to

achieve beneficial operational modes that require a hot

plasma edge, such as the “H-mode,” or high-confinement

mode. A liquid lithium wall may be the solution because

of its capability for absorbing plasma particles. The

reduction of the recycling due to the lithium would help

establish the hot plasma edge needed for high-confinement modes.
Page 5 PPPL NEWS • Spring 2001

“For me the most exciting aspect of these experiments is the chance to investigate the behavior of plasmas

with a new and different type of boundary. Experience

from TFTR [Tokamak Fusion Test Reactor] and other

experiments all over the world tells us that when we

change the wall conditions, we change the plasma contained by the wall,” said Majeski. CDX-U researchers are

hoping that the use of lithium as a wall material will lead

to new and improved modes of plasma operation.

In preparation for lithium experiments which began

last fall, a portable handling assembly was designed and

built by the University of California, San Diego. The

device, which resembles a gun carriage found on a battleship, can be wheeled out of the CDX-U area and taken

down the L-Wing freight elevator to a separate lab equipped

for fueling and maintenance. The handling assembly

contains a unique rail limiter on a retractable probe. The

rail limiter consists of a cylindrical surface about 20-cm

long and 5-cm wide. Because the limiter is a cylinder, the

area in actual contact with the plasma is a strip about a

centimeter wide.

A stainless steel mesh covers the limiter. Lithium

melts at about 181 degrees Celsius and is liquified in a

reservior above the stainless steel mesh. As lithium is

dripped on the mesh, it is automatically soaked up and

spreads across the surface of the mesh. This is because

liquid lithium resembles mercury and, like mercury, it has

a high-surface tension. The rail limiter can be heated up

to 300 degrees Celsius to insure that the lithium continues

to flow evenly over the mesh surface.

Lithium, like other alkali metals, reacts vigorously

with water, including moisture in the air. Consequently,

limiter fueling is performed in a glovebox containing

argon, an inert gas. The limiter is then brought to the

CDX-U area and inserted in the vacuum vessel via a

double gate valve airlock system. When the rail limiter is

in position, it forms the upper limiting surface for the

plasma.

During the fall of 2000, CDX-U staff successfully

demonstrated the safe and efficient handling of lithium.

Experiments underway during the latter part of 2000 were

conducted with solid and liquid lithium limiters. During

these preliminary tests, there was evidence that the lithium

was interacting with the plasma. Bands of very bright

light around the limiter indicated that lithium was being

driven off its surface.

Data from Spectrometers

Data from spectrometers showed that there was an

influx of lithium into the core of the plasma. This caused

energy to be radiated out of the plasma, not at a level

detrimental to confinement. After each experiment, when

the lithium was cooled, a coating was found on the limiter.

CDX-U scientists believe that this was lithium hydroxide,

which was formed when the hot lithium interacted with

the small amount of water vapor that was inside the

vacuum chamber. They were able to remove the coating

by bombarding the limiter with argon ions in a process

called “glow-discharge cleaning.”

Measurements were made of the light from the deuterium atoms near the limiter, and the “pumpout rate” of

the deuterium after a plasma was formed. They showed

that while recycling was reduced, it was not completely

eliminated.

In the lithium rail limiter experiments, the plasma

interacted mostly with parts of the machine not containing lithium, including limiters made of boron carbide on

the center column and on the bottom of the vacuum

vessel.

In the next series of CDX-U lithium experiments, the

area of the plasma-lithium interaction will be increased

from the modest 20 cm2 to 1,900 cm2. Researchers will

employ a “belt” or “tray” limiter that will rest all the way

around the bottom of the vacuum vessel, below the entire

plasma. Using this setup, CDX-U researchers will investigate plasmas which will indeed interact primarily with

a lithium surface. Scientists hope that the operational

experience and knowledge gained from these and subsequent lithium experiments on CDX-U will greatly advance the physics and technology base for liquid metal

first walls, a potentially critical element for the realization

of practical fusion power plants later this century. ●

Above is the head in the CDX-U vacuum chamber during argon

glow-discharge cleaning. The center of the head, where the interaction with the plasma was the strongest, still shows a coating. The

surface near each end is cleaner. The previously bare region toward

the right of the head has become “wetted” with lithium.
PPPL NEWS • Spring 2001 Page 6

DOE’s Gunn Stresses Value of Diversity

To one woman, it was a person swimming in the

middle of a pool. To another, it was a donut with a

tiny center hole. One fellow thought it was a speck in the

universe, while someone else said it was a snake looking

up from a hole in the ground.

So who was right? All of them.

Those offering answers were participating in a

simple exercise at PPPL’s Melvin B. Gottlieb Auditorium on March 1. Department of Energy (DOE)

Chicago Operations Office Manager

Marvin Gunn had drawn a large circle

with a dot in the center and asked people

around the room what it was. The drawing conjured up images as individual

as, well, each individual.

“The point of the exercise is to see

the value of diversity,” said Gunn,

who addressed all PPPL staff during a

visit to the Lab that also included a tour

of PPPL and a meeting with the Director’s

Minority Advisory Committee. “That is

what gives us the strength we need to

accomplish great things.”

Gunn opened the talk by giving a personal overview

of his lifelong interest in technology and concluded by

discussing the importance of differences among individuals and teamwork. The DOE manager recalled how

his interest in science was sparked after receiving a tool

kit for Christmas as a child. “I took an old clock radio

apart and put it back together without using half of its

original parts,” he said. His interest in technology and

science followed him throughout his high school and

college years, when he realized the need for collaboration. Building a model of an atom required teamwork, and his college group involved in the project

was melded by their shared interest. “The thing

that brought us together was science,” said Gunn,

who received a mechanical engineering degree

from Howard University before going into public

service. His philosophy about teamwork continued to guide his career at the Chicago

Operations Office, where he said he realized he could not do his job alone — nor

could anyone.

The Department of Energy Head emphasized the importance of celebrating individual differences, discussing a staff

Unity Day Celebration at his office. “We

talked about the differences in how we process information,” said Gunn, who has been

in his current position since December. He

added that individuals must be valued for

their unique capabilities and their contributions to a

team’s success. “Look at all the inventions, new ideas,

and projects — all were done by a systematic assemblage of genius ...We are all geniuses in our own right.

Organizing geniuses is a challenge, but a successful

team gets it done,” said Gunn. ●

In Remembrance

Thomas Howard Stix, one of the most original thinkers and

leading developers of the field of plasma physics, died April

16 in Princeton. He was 76 and a professor emeritus in astrophysical sciences at Princeton University. Professor Stix will be remembered not only as an outstanding scientist, educator, innovator, and

inventor, but also for his warmth, humor, and genuine concern for

people. In 1953, he joined Project Matterhorn, then a small,

classified project on Princeton’s Forrestal Campus. The project’s

aim was to harness fusion energy for peacetime use. Project

Matterhorn grew quickly and, in 1961, when Stix headed the

Experimental Division, its name was changed to the Princeton

Plasma Physics Laboratory. Stix’s work revolutionized research

in plasma physics by showing how waves could heat plasma. Stix (above, with a tokamak model) was also the author

of a classic text, “The Theory of Plasma Waves,” published in 1962, and the recipient of numerous awards. ●

Marvin Gunn
Page 7 PPPL NEWS • Spring 2001 Printed on recycled paper.

More than 160 seventh through 12th grade female

students from area schools came to PPPL on March

16 to participate in the “Expand Your Horizons MiniConference for Young Women in Science, Mathematics,

and Technology.” The conference included talks by various women in the sciences, a panel discussion, exhibits,

and lunch. Above, mini-conference participants listen to

a presentation about the NASA Goddard Space Flight

Center. ●

PPPL Outreach ...

On April 28, PPPL participated in Communiversity,

the annual town-gown festival in downtown

Princeton. Lab staff volunteered at the PPPL exhibit,

which included fusion and PPPL handouts, as well as

hands-on science demonstrations. More than 1,000 visitors saw the Lab’s exhibit. Above, PPPL engineer Henry

Carnevale fields questions about fusion. ●

Fourteen area students exhibited their science projects

on April 18 during PPPL’s annual Science Fair Day.

The Science Fair honored the 12 winners of PPPL’s

Corporate Awards, who were chosen among student

exhibitors at the North Jersey Regional Science Fair at the

County College of Morris in Randolph and at the Mercer

Science and Engineering Fair at Rider College in

Lawrenceville in March. Also honored were two special

visitors,who displayed their science projects. PPPL Engineering and Technical Infrastructure Head Michael Williams talks to an exhibitor about her science project. ●

This year’s Science-on-Saturday series at PPPL

concluded on March

17 with a talk, “Keeping the Flame Alive

— Flames of the Sydney 2000 Olympic

Games,” by Richard

Kelso. Kelso (seen

lighting the Olympic

Torch at the lecture)

described how a team

of Adelaide engineers

in Australia designed

the fuel and combustion systems for the Olympic torch

and the stadium cauldron for the Sydney Olympics. He

was the Chief Design Coordinator of the Torch Development Team and Joint Leader of the Stadium Cauldron

Design Team for the Sydney 2000 Olympics.

Science on Saturday is a wintertime series of free

lectures geared toward high school students, but open to

everyone. Started 17 years ago at PPPL, it attracts about

300 people each Saturday. This year’s series included

eight talks and was organized by PPPL’s Ronald Hatcher,

Janardhan Manickam, and James Morgan. ●

Photo by John Bennevich
PPPL NEWS • Spring 2001 Page 8

Redi Chairs APS-DPP Committee for Women

PPPL physicist Martha Redi

was recently appointed Chair

of the American Physical Society-Division of Plasma Physics

(APS-DPP) Committee for Women in Plasma Physics (CWPP).

The new committee was formed

last year.

“Plasma physics is a field in

which women have not found

much success compared to other

fields of physics. APS-DPP became aware of this last year and

formed the committee in an effort to improve the environment

for women and to work for equitable opportunities for them in the field,” said Redi, who

has been active in speaking for the women of the Division

to the APS-DPP Executive Committee and has organized

get-togethers for the women at the Annual Meeting for

several years.

An APS-DPP ad hoc committee, reporting to the

Executive Committee last year, recommended the creation of the standing committee after compiling statistics

about the number of women members and Fellows involved in the Division. The ad hoc committee was appointed in response to a letter to DPP leadership written

by Redi and signed by 20 percent of the women in the

Division. In it, they expressed concern about the low

number of women entering and remaining in the field of

plasma physics, and the difficulty women found in gaining recognition for their work — through invited talks, by

appointments to committees, and by attaining leadership

positions and funding. The ad hoc committee found that

few women were entering the field, and even fewer were

remaining and attaining Fellowship status. In 1999, there

were 111 female members of the DPP out of a total of

2,500 members, or about 4 percent. The APS has 8

percent women on average in all the divisions.

James Drake, Chair of the APS-DPP Executive Committee in 2000, said in a message posted on the DPP’s web

site, “What I found to be most alarming were the statistics

on the number of women Fellows in our field. There are

a total of seven women Fellows in the DPP compared with

450 male Fellows. Even more alarming is that among the

female Fellows in the DPP, only one is actually active in

plasma physics at the present time (as opposed to space

and astrophysics). It seems clear then that a number of our

most outstanding female members are moving out of the

field. Thus, we find ourselves in a situation where we are

not only not attracting significant

numbers of women to our field,

but we are also not able to retain

female scientists.”

When the APS-DPP Executive Committee created the

CWPP, it passed a resolution,

stating, in part, “The DPP must

promote the recruitment, participation, and advancement of

women in plasma physics, and

ensure that women are fairly represented, both scientifically

through invited talks, and in activities and leadership positions

as officers, executive committee

members, and committee chairs.” Besides Redi, the other

Committee for Women in Plasma Physics members are

Gail Glendinning, Lawrence Livermore National Laboratory; Professor Noah Hershkowitz, University of Wisconsin; Professor Mary K. Hudson, Dartmouth College;

Professor David Newman, University of Alaska; Mary

Ann Sweeney, Sandia National Laboratories; Cha-Mei

Tang, Creatv Micro Tech, Inc.; Professor Linda Vahala,

Old Dominion University; and Professor Ellen Zweibel,

University of Colorado, Boulder.

“We are asked to keep track of how APS-DPP is

doing with respect to representation of women members

on the Annual Meeting Program Committee, invited

speakers, and other committees. We also are asked to

submit names of women for Fellowship nomination,”

said Redi, who also has been asked to work with the APS

Committee on the Status of Women in Physics. “For

example, this year a woman plasma physicist who is a

member of the National Academy of Sciences may become an APS-DPP Fellow. APS-DPP has shown real

concern and we are hopeful that the next generation of

women will find plasma physics fascinating, challenging,

and with opportunities for success.” ●

Martha Redi

The U. S. Department of Energy’s (DOE’s) National Laboratories house world-class facilities where more than 30,000

scientists and engineers perform cutting-edge research spanning DOE’s science, energy, national security, and environmental quality missions. Interested in the latest achievements of the National Laboratories? Then visit the DOE

Pulse at: http://www.ornl.gov/news/pulse/.