Transcript No Slide Title

Plasma physics: innovation in
energy & industrial technology
Prof. Jeffrey Harris
Plasma Research Laboratory
Research School of Physical Sciences & Engineering
Institute of Advanced Studies
Australian National University
14th National Congress of the
Australian Institute of Physics
Adelaide, December 10-15, 2000
Plasma
antenna:
comms
& radar
Fusion energy physics
Plasma processing
of electronic materials
Power technology
Contributors
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Australian National University
University of Canberra
University of New England
University of Sydney
Defence Science & Technology Organisation
Kyoto University
National Institute of Fusion Science (Japan)
Princeton University
Walshe & Associates
Plasma fusion reactions drive the stars
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Plasma comprises 99% of the universe
Many reactions
Energy production
Synthesis of heavier nuclei
Primordial physics
Why work on fusion energy?
• World electricity use  2% / year
1995
– 2  increase in total energy use
– 10% / year in Asia
• 70% from fossil fuels
Other
renewables
1%
Hydro
7%
Nuclear
21%
Solid Fuels
42%
– Fastest growing: natural gas
• Problem time-scale ~ 50-100 years
Oil
10%
Gas
19%
– Supply problems: price, disruptions
– Pollutants, global warming
• Fusion  increased safety, reduced radioactive waste
– Fission reactor:
• 1 year of fuel (uranium, plutonium isotopes)
• Fuel cycle issues
– Fusion reactor:
• 30 s of fuel (hydrogen isotopes)
Basic plasma physics
• Ionized gas that is
charge neutral over
Debye scale length:
e = (kTe/ne 2) ~ 10-2 mm
• Behaves as fluid and as
particles.
• Larmor gyration in
magnetic field
rL = VT/ c
c = eB/m
Progress toward fusion
In the last 20 years,
experiments have
advanced orders of
magnitude in fusion
confinement parameters
and are now in the
reactor regime.
D-T experiments in the
Joint European Torus
produced 16 MW of
neutrons for ~ 1 s.
Worldwide effort to make fusion reactors economically viable
• Confinement of plasma energy  reactor size
Factors ~ 2-5 critical
"Improved confinement" modes
Underlying physics of turbulence
Need for fundamental advances
• Fatter "spherical" tokamak (ST)
More stable, and compact
New, large STs in US & Europe
• Eliminate plasma current
stellarator
External helical fields
LHD (Japan)—just started operation
Wendelstein-VIIX—operates 2006
• Huge endeavors, staff in hundreds
 Need (and room) for agile fundamental research  role for Australia
H-1NF Heliac: from concept to experiment
• Magnet coils & structure designed
by PRL, fabricated by RSPhysSE
mechanical workshop
• Req'd precision of coils ~ 2 mm
Computed
Measured
w/ electron
beams
Major radius = 1 m
Plasma minor radius = 0.2 m
Top view of H-1NF with vessel lid removed
Extensive in-vessel work req'd for diagnostic installation
H-1 operation at low field (< 0.2 T) & power (< 100 kW)
 confinement transitions
 similar to larger devices at 20  higher power
D3D tokamak
H-1
• Low temperatures in H-1 permit study w/ simple diagnostics.
• Change of n(r), turbulence suppression, even reversal of induced flux.
• Collaboration w/ larger exp'ts to elucidate mechanisms, recipes.
Radial electric field changes with p
0
0
E 
-5
 Is  p
-10
V/cm
mA/cm
-0.1
-0.2
-15
Averages over (0.25 <  < 1)
-0.3
-20
-0.4
30
32
34
36
t (ms)
38
-25
40
H-1  national research facility
with new capital funding of $A 8.7M
• Increase magnetic field: 2 kG  10 kG
– 12 MW, 14 kA DC power supply (with ABB, Cegelec, TMC)
• Increase plasma heating power:
100 kW (7 Mhz)  500 kW (4-26 MHz, 28 GHz)
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200 kW, 28 GHz gyrotron from NIFS/Kyoto Univ. (installed)
250 kW, 6-26 MHz transmitter from Radio Australia (installed)
Systems integration in progress
Decision on additional heating in 2001-2002
Major port modifications on vacuum vessel
Improve vacuum pumping system
New diagnostics (microwaves, spectroscopy, Thomson scatt.)
Collaboration with researchers from Australian universities and
overseas (Japan, US)
Poster TF-161
H-1NF 12MW Power Supply: Concept
H-1NF power supply:
power of a Very Fast Train
precision of a laboratory instrument
Ripple
 Causes “shimmer” in
configuration
 dB/dt  EMF 
unwanted plasma
current
 Possible reconnections
and heating at surface
Achieved:
• Ripple current << 1Amp
• dI/dt (0-30Hz) < 10A/s
Next: minimise power Line
disturbance @ max. load
supply drop
ANU
• Harmonics
supply drop
ANU
GRID
GRID
– 24 phase diode bridge, full
conduction angle
• Disturbances
H-1
current
– ramp load smoothly by
dumping power
• Droop
H-1
total
compensation
V
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AC line droop
corrected
– Switched capacitor
“overcompensation”
• Commercialisation
– Work w/ companies
involved in H-1NF
– Power quality control for
industry, mining
-4% droop
DC
current
critical accuracy
time window
1 second
permanent harmonic
filter (11kV, 2.5MVAr)
BBC transmitter (from Radio Australia)
• 6-26 MHz, 250 kW
• Refurbish by British Aerospace
• New coax from NIFS
• Use for helicon, ICRF heating
28 GHz ECH system
Microwave scattering
• Microwaves @ 132 GHz
scattered by density
fluctuations  turbulence
and confinement studies
V
k
Angle (cm^-1) (cm^3)
H5 20°
9.6
5.08
H4 35°
16.6
3.96
H3 50°
23.3
3.88
H2 65°
29.7
4.06
H1
Modulated Optical Solid-State Spectrometer (MOSS)
MOSS principle
• Fringe decay gives broadening  temperature
• Fringe phase gives shift  flow
MOSS camera used to measure Ti, flows in H-1NF
• 2-D simultaneous
measurements of ion
temperature & flow
• Other plasma
spectroscopy
applications being
explored with NIFS
(Japan) & Princeton
(US).
• Additional
applications to
emissive media
under consideration.
Multiple metallic antennas pose problems for design
of military platforms:
• radar cross-section
• mutual coupling
 Plasmas as flexible substitute?
Plasma rf response depends on frequency
Plasma
j = -i0(r-1)E
r = 1 - pe2/( + i)
pe2 = nee2/0 me (plasma frequency)
 = collision frequency
Metal
j = E
r = 1 - i0
• For  >> , plasma  metal with  = nee2/me
• For  < pe , plasma is a reflector [fcut-off = 9 (ne/1012 cm–3)1/2 GHz]
• For  ~ pe , phase velocity varies strongly with density
(dispersive dielectric)
• For  > pe , wave propagates inside plasma
Plasma antennas use these variations to create special effects
The plasma antenna
• Zero radar x-c out-ofband; no x-c when not
energised
• Efficient (50%), lownoise transmission
demonstrated at 7-200
MHz.
• Possibilities for
HF/VHF adaptive
arrays, radar,
extension to µwaves.
No electrode
Excitation on sleeve
electrode
Match Box
Plasma antennas used for simple FM
communications experiment
The surface wave driven plasma and metal have
similar noise spectra over the HF band
0 dBm 21 MHz
dB
reference signal
Zero freq. marker
A 50 Hz AC current driven plasma tube has
much greater noise over the HF band
0 dBm 21 MHz
dB
reference signal
Zero freq. marker
Plasma antenna can be used for beam forming
• Cardioid pattern reproduced with the plasma antenna
• Programmable array of elements  rotate patterns
Metal
Transmit Frequency 600 MHz
Theory
Experiment
Array concept under study
Plasma
LightSword VHF plasma antenna demonstrator
Dielectric
tube
• Two frequencies:
140 MHz pump
200 W pk, 20% duty
Shock
absorbing
rings
ƒ = 20–40 MHz
20-40 MHz for comms.
2.2 m
• Delivered to DSTO in
February, 2000
Coupling
sleeve
Mounting
plate
Matching
box
Transceiver
(50-200 W)
Plasma lense–theory
Radial gradient in plasma density  gradient in refractive index
Ray trace and radiation pattern for
35 GHz refraction at n0 = 8  1013 cm–3
Plasma lense–experiment @ 35 GHz
plasma drive
13 MHz, 1 kW pk
80 µs pulse
calculated
density
profile
permanent magnets
 diverging B
Cell size shrinks
to a few cm3 for
f ~ 100 GHz
Adventurous communications projects (2000-2001)
• Broadband VHF data transmission
– Low cost long range connections to remote regions
– 30-100 MHz bands will be vacated in Australia in 2006 with
advent of digital TV
– Trying spread-spectrum & frequency hopping with large
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– Plasmas as antenna switching elements
– Broadband
– Obviate ringing?
– Low-power
– Low-noise?
• Tunable photonic band gap antenna for microwaves
• Support from DSTO, ARC, and Motorola-USA
Plasma processing of electronic materials
Helicon plasma source pioneered @ ANU
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RF driven, high-density, low-power
Thin-film deposition and etching
Next-generation semiconductor processing
Optical waveguide applications
Major industrial support ($M’s)
Helicon Activated Reactive Evaporation
(HARE)
Electron-beam evaporator +
high density plasma source.
Permits fabrication of exotic
thin films, e.g. germaniumsilicon films for optical
devices.
Avoids problems of hazardous
precursor gases (e.g., halides).
Commercialised in Japan
Conclusions
• Research environment in Australia requires
synergy between long-term and near-term
research.
• In plasma physics, we innovate in fusion,
materials processing, telecommunications, &
power engineering.
• Multidisciplinary ferment of plasma research
makes this possible.
To learn more . . .
Plasma @ AIP: Thurs. & Fri afternoon
Plasma Physics Mini-Summer School
29 January-2 February, 2001 @ ANU
Support available
13th International Stellarator Workshop
24-28 September, 2001 @ ANU
http://rsphysse.anu.edu.au/prl/
e-mail: [email protected]