Plasma Lighting Technology
J. Sager (Retired - NASA, Kennedy Space Center, Florida, USA)
and R. Wheeler (NASA, Kennedy Space Center, Florida, USA)
Presented in “CONTROLLED ENVIRONMENTS: TECHNOLOGY
AND PRACTICE”, Session 2 - LIGHT IN CONTROLLED
ENVIRONMENTS (Chair: B. Bugbee)
The 4th International Conference of the UK CEUG, the North
American NCERA-101 and the Australasian ACEWG
Downing College, Cambridge, UK
9 September 2012
Plasma Lamp Technology
• Plasma lamps are part of the family of electrodeless lamps including
fluorescent induction, sulfur plasma and solid state plasma lamps.
– Nicola Tesla demonstrated the concept with wireless transfer of power to
electrodeless fluorescent and incandescent lamps ca. 1894 (United States
Patent 454622).
– A plasma lamp system contains an electrodeless bulb and an excitation source,
such as a magnetron (microwave generator-2.45 GHz) or radio frequency (RF)
generator.
– A plasma lamp emits light from the excited plasma of sulfur or halides and
generates a continuous spectrum.
• Currently both the sulfur plasma and the solid state plasma lamps are
used in limited horticultural applications.
Maltani Lighting sulfur lamp
Luxim solid state lamp (LEP)
Sulfur Plasma Lamp
• The sulfur lamp has an evacuated quartz bulb partly filled with an inert
gas, e.g., argon (Ar), a small amount (mg) of sulfur (S), and, perhaps, some
other compounds such as InBr, CaBr2 or other halides to enhance the
output spectrum in the red (600 to 700 nm) or far-red (700 to 740 nm)
regions of the spectrum.
• The sulfur plasma lamp was developed by Michael Ury and Chuck Wood of
Fusion Lighting Systems, Inc. in 1980 and they commercialized several
versions from 1995 to 1999.
– In the United States, development of the lamp was supported by NASA Small
Business Innovative Research (SBIR) Phase 1 and Phase 2 contracts from 1992
to 1995.
– In 1997 Fusion Lighting was awarded a NASA SBIR Phase 1 contract for
development of an RF excited plasma lamp and developed a prototype. The
company went bankrupt due to failure of the magnetron circuitry in the sulfur
plasma lamps before completion of the contract.
Sulfur Plasma Lamp
• The bulb or the microwave excitation field, as is the case with the Maltani
(Taewon) Lighting Co. circularly polarized microwaves (CPM) design, must
be rotated to maintain uniform plasma flow and high irradiance.
– This rotation uniformly heats the plasma, avoids melting the bulb and
increases the luminous efficiency obtained at a given power, e.g., the
efficiency of the SOLAR-1000 lamp went up form 50 to 100 lm/W.
– Radiative efficiency is very high; up to 70% of power coupled into the plasma
can be emitted as (visible) light.
• The application of the sulfur plasma lamp to crop production was
investigated throughout the world (North American, Europe, Australia and
Asia).
• “Light pipes”, initially developed by Loren Whitehead (TIR) using 3M
materials, have been used in warehouses, parking lots and museums.
Sulfur lamp - Light pipe, 2 m to 12 m length, and ~0.3 m diameter
Sulfur Plasma Lamps
Sulfur Plasma Bulbs
Failed bulb on right courtesy of Dennis Wildman
Plasma International - AS1300
Sulfur Plasma Lamp Specifications
Initial (Old)*
Manufacturer
Model
Input Lumen Photon CCT CRI
(W) Efficacy Efficacy (K) (Ra)
(lm/W) (µmol/J)
Fusion
Solar 1000 1425
96
1.4
6000 86
Lighting
(Light Drive
1000)
Hutchins
VBL-3400E 5000
89
1.3
6700 85
International (white)
Ltd.
(Fusion
HIIQ-LI)
LG Electronics PLS-PSH07 730
54
1.4
6400 85
System Notes
22 kg,
rotating lamp
RS-232 cont’l,
rotating lamp
19 kg,
rotating lamp
* Manufacturer/models named are for example only, listing is not inclusive.
Sulfur Plasma Lamp Specifications
Current*
Manufacturer
Model
Input Lumen Photon CCT CRI System Notes
(W) Efficacy Efficacy (K) (Ra)
(lm/W) (µmol/J)
H&K
PLS- KPSH
700RI
730
54
1.4
6500
80
20 kg,
rotating lamp
Plasma
International
Plasma - i
AS1300
1360
100
1.3
6000
86
22 kg,
rotating lamp
Plasma
International
LGE PLS
700
730
54
1.4
6100
90
rotating lamp
Maltani
Lighting Co.
(Taewon )
SolaRay
1100
62
2.0
5300
96
Non-rotating
lamp (CPM)
* Manufacturer/models named are for example only, listing is not inclusive.
Solid State Plasma Lamp
• A radio-frequency (RF) signal is generated, amplified and guided into the
ceramic resonator, called the “puck”.
• The puck concentrates the RF field, delivering energy to the fully-sealed
quartz lamp, ionizes the gasses and metal halides in the lamp - creating an
intense source of white (broad spectrum) light.
• The back of the lamp is a highly reflective material to reflect light in the
forward direction.
• The color of the light is tailored by the fill chemistry inside the lamp to
provide a naturally white and high color rendering light.
Solid State Plasma (LEP) Lamps
Gavita PRO 300
Luxim Light Emitting Plasma (LEP) System
Chameleon Solar Genesis
Solid State Plasma Lamp Specifications*
Manufacturer
Model
Luxim
GRO-40
(LEP)
280
50
1.1
5300
94
Source (puck)
only
Gavita
PRO 300
(LEP)
300
60
1.0
5600
94
11.7 kg
Solar
301
Genesis
(LEP)
Grn-house 295
Grow
(LEP)
56
1.0
5600
95
8.6 kg
51
1.0
5300
95
8.6 kg
Chameleon
Stray Light
Input Lumen Photon CCT CRI System Notes
(W) Efficacy Efficacy (K) (Ra)
(lm/W) (µmol/J)
* Manufacturer/models named are for example only, listing is not inclusive.
Comparative Lamp Specifications*
Type lamp
Model
Input Lumen Photon YPF/ PPS System Notes
(W) Efficacy Efficacy PPF (%)
(lm/W) (µmol/J) ** ***
Sulfur Plasma Solar 1000 1425
96
1.4
0.86 78
22 kg,
rotating lamp
Solid State
PRO 300
300
60
1.0
0.90 79 11.7 kg, single
Plasma (LEP)
est. est.
puck
Fluorescent
F54T5/
54
93
1.3
0.89 83
841/HO
Metal Halide MH1000/ 1080
108
1.2
0.90 80
Ceramic
CDM-T
340
105
1.9
0.91 81
Metal Halide Elite Agro
High Pressure LU1000 / 1060
123
1.5
0.95 85
Sodium
LED (Illumitex) Surexi F3
314
1.3
0.93 85 strip array x 6,
est. est.
54 LEDs
rectangular
LED (Lighting VividGro
300
50
1.3
0.90 82
Science Grp.)
est. est. array, 64 LEDs
* Manufacturer/models named are for example only, listing is not inclusive; ** YPF = yield photon flux;
*** PPS = phytochrome photostationary state ; (YPF/PPF & PPS data from B. Bugbee and G. Deitzer)
Sulfur Lamp Crop Growth Comparisons
Crop
Lettuce
(Ostenata)
Lettuce
(Waldmann’s
Green)
Cucumber
(Poinsett)
Cucumber
(Hoffmann’s
Giganta)
Rice
(4 x day
neutral
cultivars)
Radish
(Cherry Belle)
DAP
(days)
26
28
14
13
TO
HARVEST
28
PPF
Sulfur
(µmol m-2s -1) Lamp
525/250/ 3.13g
250/ (dw)
250/250/ 2594g
250/ (fw)
MH or Fluor- Solar
HPS escent
2.70g 1.77g
---
2440g 2120g
500/500/ 902g 691g
-/(dw)
100/100/ 1001g 611g
100/ (dw)
1000/ - /
- /~1000
250/250/
250/
95.1g --(dw)
37.3g
(rice)
852g 690g
(dw)
---
---
---
440g
---
---
38.4g
Reference
Both et al.
1993
Goins et al.
2000
Krizek et al.
1998
Hogewoning
et al. 2010
Kozai et al.
1995
18.6g
720g
---
Goins et al.
2000
Solid State Plasma Lamp
Crop Growth Comparisons
Observed plant responses - Solid State Plasma vs Fluorescent /Tungsten*
(240 µmol m-2s -1, 14 p-p, T-day = 20C / T-night = 15C, RH = 65 %)
Barley: Plants similar - slightly taller and denser under plasma. Grain formed under
fluorescent, but not under plasma.
Pea:
Plasma plants smaller with smaller leaves and less pods than fluorescent.
Lettuce: Plasma plants taller and more open leaf structure, neither forming a heart.
Grass:
Plasma plants slightly denser.
Carrot: Plasma plants a bit taller (drawn) and roots smaller.
Clover : Plasma plants poorer.
Barley
Pea
Lettuce
Carrot
*Observed data from Allan Sim, The James Hutton Institute, Invergowrie Dundee, Scotland
Solid State Plasma Lamp
Crop Growth Comparisons
Use of Light Emitting Plasma (LEP) Lamps As a New Source of Artificial Light
in Growing Lettuce and Tomato*
• Four cultivars of lettuce (Butterhead, Iceberg A, Little Caesar, and Simpson
Elite) were grown under LEP, high pressure sodium (HPS), and metal halide
(MH) lamps with approximate PPF levels (350–400 µmol·m-2·s-1).
– The biomass yield was similar under the three different lamps.
– However, the architecture of lettuce plants grown under LEP was more
desirable than that obtained under other lamps.
• Four tomato cultivars (Cobra, Geronimo, Masada, and Trust) were grown
under LEP and HPS lamps.
– The plants grown under LEP were shorter and more compact than those
grown under HPS, while showing higher biomass yield.
– The solid content of fruits harvested was slightly higher for plants grown
under LEP lamps compared to HPS lighting.
– LEP lamps consumed about 25% less electricity than HPS lamps for the same
wattage lamps producing similar PPF levels.
– Both LEP and HPS lamps allowed the production of commercial quality tomato
fruits when used as sole sources of artificial lighting.
* C. W. Lee, Ju Ho Choi and L. Brower, North Dakota State University (Poster, 31 July, 2012
ASHS Meeting, Miami, FL)
Plasma Lamps Pros
– Continuous spectra
– Positive response in most plant growth tests
– Environmentally friendly bulb fill, no Hg (Some metal halides may
contain Hg)
– High lumen and PAR efficacy results in energy savings
– High irradiance, point source requiring optimal luminaire design for
uniform distribution
– Adaptable to “light pipes”
– Rapid start times; < 1 minute
– Fast re-strike times; < 2 minutes
– Dimmable units are available
– Minimal spectral changes with age
– Fill niche horticultural applications
Plasma Lamps Cons
– Unit life and reliability have not reached expected life time
• The bulbs last for years, but the magnetron and the motor(s) have failed
in a short time (1st generation units had 50% of the magnetrons burn out
within 3-6 months).
• The lamps operate at very high temperatures (900-1200 C). These high
temperatures lead to a break down in the luminaires and high infrared
radiation emission to the crop canopy or plastics used nearby, e.g., lenses.
– The sulfur spectrum is noticeably green; people and plants do not
“like” greenish light
– EMI shielding must be maintained for safety and proper
communications maintenance
– Solid State Plasma (LEP) bulbs are position sensitive and must be
oriented for intended operating position
– Limited choice of lamp manufacturers and lamp wattages
• Sulfur lamps ; > 700 W
• LEP lamps ; < 300 W
– Longevity of Manufacturers (?)
Acknowledgements:
• My co-presenter, Ray Wheeler, for providing numerous references and
editing the presentation.
• Donald Krizek for editing the presentation.
• Allan Sim for sharing his observations with LEP lamps.
• Sulfur lamp failure example courtesy of Dennis Wildman, Ecotron
Electronics Engr., Imperial College London.
• Kevin Lucks, Lighting Consultant, for sharing his plasma lamp portfolio.
• The CEUG organizing committee for their support.
• Lynton Incoll for his quest for new CE technology and the invitation to
make this presentation.
Thank You!
QUESTIONS?