Chapter High Pressure Discharge Lamps
Slide 1
Incoherent Light Sources
Prof. Dr. T. Jüstel
6. High Pressure Discharge Lamps
Content
6.1 Overview of Low- and High-Pressure Discharge Lamps
6.2 Spectrum of a Hg Discharge
6.3 The High-Pressure Mercury Lamp (HP)
6.4 Phosphors for High-Pressure Mercury Lamps
6.5 The Electrode
6.6 The Electrode Feed Through
6.7 Types of Reflectors
6.8 Application of HP-Lamps
6.9 The High-Pressure Sodium Lamp (HPS)
6.10 Application of HPS Lamps
6.11 Metal-Halide Lamps (MH)
6.12 Photometric Data in Comparison
6.13 Applications of MH Lamps
6.14 UHP-Lamps
6.15 New Developments
Chapter High Pressure Discharge Lamps
Slide 2
Incoherent Light Sources
Prof. Dr. T. Jüstel
Hg low-pressure (TL)
Na low-pressure (SOX)
Hg high-pressure (HPMV = high pressure
metal vapour)
Na high-pressure (HPS = high pressure sod.)
Metal-halide high-pressure (MH)
HID = High Intensity Discharge
6.1 Overview of Low- and High-Pressure Discharge Lamps
Hg low-pressure (CFL, PL)
Chapter High Pressure Discharge Lamps
Slide 3
Incoherent Light Sources
Prof. Dr. T. Jüstel
Emissionsspektrum von Hg
l [nm]
200 300 400 500 600
18
5
25
4
57
7
54
6
43
6
40
8
31
3
36
6
Energy level scheme of Hg Schematic emission spectrum of a
Hg-discharge at a low pressure [~ mbar]
6.2 Spectrum of Hg Discharges
Ionization level (~ 10.4 eV)
6 ( S ) 1 0
6 ( P ) 3 0
6 ( P ) 3 1
6 ( P ) 3 2
7 ( S ) 3 1
6 ( D ) 3 1
7 ( S ) 1 0
6 ( P ) 1 1
L e v
e l e
n e r g
y [ e
V ]
1 8 5
n m
0
1 0
5
Chapter High Pressure Discharge Lamps
Slide 4
Incoherent Light Sources
Prof. Dr. T. Jüstel
Pressure dependence of the lumen output
l in nm 200 300 400 500 600
18
5
25
4
57
7
54
6
43
6
40
8
31
3
36
6
l in nm 200 300 400 500 600
18
5 25
4
57
7
54
6
43
6
40
8
31
3
36
6
Pressure
h [
lm/W
]
100
60
10 mbar 1 bar
6.2 Spectrum of Hg Discharges
Pressure increase
60 lm/W Why is this of interest for lamps?
Good imaging properties
High luminance
100 lm/W
20 lm/W 20
Ph
osp
hor
Chapter High Pressure Discharge Lamps
Slide 5
Incoherent Light Sources
Prof. Dr. T. Jüstel
6.2 Spectrum of Hg Discharges
Measured spectra of water-cooled
capillary mercury discharge lamps
P = 25 atm.
P = 30 atm.
P = 100 atm.
P = 150 atm.
Source: W. Elenbaas,
Quecksilberdampf-
Hochdrucklampen (1966)
Chapter High Pressure Discharge Lamps
Slide 6
Incoherent Light Sources
Prof. Dr. T. Jüstel
Evacuated outer bulb
Burner (Hg, noble gas = starting
Gas, mostly Xe)
Ballast
6.3 The High-Pressure Mercury Lamp (HP)
Electrode
Melting
Chapter High Pressure Discharge Lamps
Slide 7
Incoherent Light Sources
Prof. Dr. T. Jüstel
Blue-white light due to the
lack of red radiation in the
emission spectrum
Solution: Phosphor!
h = 60 lm/W
Ra = 20
Lifetime = 20.000 h
6.4 Phosphors for High-Pressure Mercury Lamps
400 500 600 700 800
0
1
2
3
4
5
Inte
nsity [
a.u
.]
Wavelength [nm]
Chapter High Pressure Discharge Lamps
Slide 8
Incoherent Light Sources
Prof. Dr. T. Jüstel
Suitable phosphors
(Sr,Mg)3(PO4)2:Sn 620 nm Broadband emission
Mg4GeO5.5F:Mn 660 nm Line emission
YVO4:Eu 620 nm Line emission
Y(V,P)O4:Eu 620 nm Line emission
h = 60 lm/W
Ra = 50
Lifetime = 20.000 h
6.4 Phosphors for High-Pressure Mercury Lamps
400 500 600 700 800
0
1
2
3
4
5
Phosphor
Plasma
Re
lative
In
ten
sity [
a.u
.]
Wavelength [nm]
Chapter High Pressure Discharge Lamps
Slide 9
Incoherent Light Sources
Prof. Dr. T. Jüstel
Sn2+ or Mn4+ phosphors
as UV Red converter
Problem: Low lumen equivalent of these phosphors
6.4 Phosphors for High-Pressure Mercury Lamps
Luminescence spectra of (Sr,Mg)3(PO4)2:Sn
Luminescence spectra of Mg4GeO5.5F:Mn
l [nm]
Inte
nsi
ty
100 200 300 400 500 600 700 8000,0
0,2
0,4
0,6
0,8
1,0
lmax = 658 nm
QE254 = 81 %
RQ254 = 7%
x = 0.713
y = 0.287
LE = 80 lm/W
Emission spectrum
Excitation spectrum
Reflection spectrum
Re
lative
in
ten
sity
Sample U601Wavelength [nm]
100 200 300 400 500 600 700 8000,0
0,2
0,4
0,6
0,8
1,0
lmax = 620 nm
QE254 = 79 %
RQ254 = 5%
x = 0.549
y = 0.426
LE = 150 lm/W
Emission spectrum
Excitation spectrum
Reflection spectrum
Re
lative
in
ten
sity
Sample U2024Wavelength [nm]
Chapter High Pressure Discharge Lamps
Slide 10
Incoherent Light Sources
Prof. Dr. T. Jüstel
YVO4:Eu3+ phosphors - Thermal behavior
The luminous efficacy under UV-A excitation increases
up to about 300 °C
Cause: Increase in spectral overlap with Hg
high-pressure discharge spectrum
6.4 Phosphors for High-Pressure Mercury Lamps
Excitation spectra of YVO4:Eu
250 300 350 4000,00
0,05
0,10
0,15
0,20
0,25
0,30
monitored at 619 nm
U737025C
U737075C
U737150C
U737200C
U737250C
U737300C
U737330C
Em
issio
n in
ten
sity [a
.u.]
Wavelength [nm]
550 600 650 700 7500
20000
40000
60000
80000
excitation at 300 nm
U737025C
U737075C
U737150C
U737200C
U737250C
U737300C
U737330C
Em
issio
n in
ten
sity [
a.u
.]
Wavelength [nm]
0 50 100 150 200 250 300 350
0
1
2
3
4
5
6
7
8 integral 254 nm exc.
Integral 300 nm exc.
Integral 350 nm exc.
Rela
tive e
mis
sio
n inte
nsity
Temperature [°C]
Emission spectra of YVO4:Eu
Luminescence intensity as a function of
temperature and excitation wavelength
Chapter High Pressure Discharge Lamps
Slide 11
Incoherent Light Sources
Prof. Dr. T. Jüstel
Hg low-pressure Hg high-pressure
36 W 400 W
I = 0.36 A I = 4 A
Tungsten + emitter Tungsten + emitter
BaO / SrO / CaO BaO / SrO / Y2O3 / ThO2
T = 1350 K T = 2000 - 3000 K
0.5 cm 1.0 cm
6.5 The Electrode
Chapter High Pressure Discharge Lamps
Slide 12
Incoherent Light Sources
Prof. Dr. T. Jüstel
Tungsten Very thin
Mo- or Nb-foil
Molybdenum
Plasma
Problem: Different thermal expansion coefficients SiO2 a = 0.5*10-6 K-1
W a = 4.3*10-6 K-1
Mo a = 2.8*10-6 K-1
Quartz (1000 °C)
6.6 The Electrode Feedthrough
Chapter High Pressure Discharge Lamps
Slide 13
Incoherent Light Sources
Prof. Dr. T. Jüstel
Parabolic reflectors Elliptical reflectors
y = x2
Focal point (light source)
Only possible if the light source is point like
An ellipse has two focal points
HID-lamps
6.7 Types of Reflectors
Chapter High Pressure Discharge Lamps
Slide 14
Incoherent Light Sources
Prof. Dr. T. Jüstel
In street lighting (outdoor lighting)
h = 60 lm/W
Ra = 50
Lifetime = 20.000 h
P = 100 W - 2000 W
6.8 Application of HP-Lamps
Chapter High Pressure Discharge Lamps
Slide 15
Incoherent Light Sources
Prof. Dr. T. Jüstel
6.9 The High-Pressure Sodium Lamp (HPS)
l in nm
300 400 500 600 700
58
9 n
m
Na-pressure
h in lm/W 200
120
10 mbar 1 bar
Na low-pressure
Lamp (0.01 mbar)
l in nm
300 400 500 600 700
Na high-pressure
Lamp (100 mbar) Pressure increase
Pressure dependence of the lumen output
58
9 n
m
Chapter High Pressure Discharge Lamps
Slide 16
Incoherent Light Sources
Prof. Dr. T. Jüstel
Problem: Na reacts at high temperatures with the quartz glass wall
4 Na + SiO2 2 Na2O + Si
Solution: Transparent, high temperature resistant
material, which does not react with Na
Al2O3-ceramics (corundum): MgO, CaO, B2O3-Additives
(DSA = densely sintered alumina)
Pressure, 1200 °C
Nb or Mo
6.9 The High-Pressure Sodium Lamp (HPS)
20 mm
Polycrystalline structure
Crystal
Chapter High Pressure Discharge Lamps
Slide 17
Incoherent Light Sources
Prof. Dr. T. Jüstel
Widening of the Na-line and self-
absorption leads to a spectral hole in the
emission spectrum at around 589 nm
pNa = 150 mbar (saturated)
pHg = 1000 mbar (buffer gas)
pXe = 100 mbar (start gas)
h = 90 - 120 lm/W
Ra = 20 – 50 (pressure dependent)
Tc = 1930 K
n=1
n=2
n=3
589 nm
(589 + x) nm (red-shift)
(589 - x) nm (blue-shift)
6.9 The High-Pressure Sodium Lamp (HPS)
Chapter High Pressure Discharge Lamps
Slide 18
Incoherent Light Sources
Prof. Dr. T. Jüstel
Architectural and street lighting
6.10 Application of HPS Lamps
Chapter High Pressure Discharge Lamps
Slide 19
Incoherent Light Sources
Prof. Dr. T. Jüstel
In Tl Na 451 535 589
SnBr/SnI-molecule emitters
DyI-molecule emitters
Filling: NaI - TlI - InI
SnBr2 - SnI2
NaI - DyI3 (SSTV)
NaI - ScI3 (automobile headlight)
Goal: High h & color rendering
6.11 Metal-Halide High-Pressure Lamps
Chapter High Pressure Discharge Lamps
Slide 20
Incoherent Light Sources
Prof. Dr. T. Jüstel
589 nm
(Na)
451 nm
(In)
535 nm
(Tl)
HPI (High Pressure Iodide) lamps
6.11 Metal-Halide High-Pressure Lamps
Chapter High Pressure Discharge Lamps
Slide 21
Incoherent Light Sources
Prof. Dr. T. Jüstel
Hg / NaI / TlI / DyI3 / Ar
P = 75 W
Na
Dy
Hg
Tl
Hg
atomic line and molecular radiation
Vl Prad / P 60 % Prad,vis / P 33 %
Spectral Intensity of CDM (70 W)
Hg / NaJ / TlJ / DyJ3 / Ar
0.00
0.05
0.10
0.15
0.20
0.25
0.30
350 400 450 500 550 600 650 700 750 800
l [nm]
I [W
/nm
]
Hg
6.11 Metal-Halide High-Pressure Lamps
Spectrum of a MH lamp
Chapter High Pressure Discharge Lamps
Slide 22
Incoherent Light Sources
Prof. Dr. T. Jüstel
Filling of metal halide lamps
Lamp starting (starting gas)
Noble gases: Ar or Xe (xenon lamps) → Penning effect
Radioactive substances: 85Kr, 147Pm
Operating voltage
• Hg
• Trend towards the substitution of Hg (environmental aspect) → Zn
Light emission
• Hg
• Metal halides MeXn (Me = Na, In, Tl, Sc, Sn, Dy, ...)
6.11 Metal-Halide High-Pressure Lamps
Chapter High Pressure Discharge Lamps
Slide 23
Incoherent Light Sources
Prof. Dr. T. Jüstel
Improvement h (lm/W) Ra Color temperature Tc [K]
High Pressure Hg 60 20 6000
+ phosphor 60 50 3800
High Pressure Na 60 - 130 20 2000
Xe-pressure 80 - 150 20 2000
Na-pressure 60 - 90 60 2200
Metal Halide HPI (NaI-TlI-InI) 70 - 80 70 3800 - 4200
SnBr2-SnI2 70 90
NaI-DyI3 75 - 80 90 3800 - 5600
NaI-ScI3 80 - 90 75 3600 - 4200
6.12 Photometric Data in Comparison
Chapter High Pressure Discharge Lamps
Slide 24
Incoherent Light Sources
Prof. Dr. T. Jüstel
HPI Street lighting
(NaI-TlI-InI) Architectural lighting
Sports field lighting
Tin Older type of lamp
is replaced by MH
NaI-DyI3 Sports field lighting
NaI-ScI3 Shop lighting
Studio-stage-TV (SSTV)
Automotive headlights
NaI-ScI3 + Hg + Xe (blue)
6.13 Applications of MH Lamps
Chapter High Pressure Discharge Lamps
Slide 25
Incoherent Light Sources
Prof. Dr. T. Jüstel
SSTV market = Stage-Studio-TV
Reflector
Spherical
mirror f
Fresnel-lens
Farbtemperatur = 5600 K
6.13 Applications of MH Lamps
Chapter High Pressure Discharge Lamps
Slide 26
Incoherent Light Sources
Prof. Dr. T. Jüstel
In the „beamer“
6.13 Applications of MH Lamps
Chapter High Pressure Discharge Lamps
Slide 27
Incoherent Light Sources
Prof. Dr. T. Jüstel
Construction of a beamer
A projector is actually a slide projector (diascope)!
Lamp at the focal point
in a parabolic reflector
Collecting
lens
Slide
In a beamer the slide
is replaced by a small
LCD screen or by a DMD
(Digital Mirror Device)
Projection
screen
6.13 Applications of MH Lamps
Chapter High Pressure Discharge Lamps
Slide 28
Incoherent Light Sources
Prof. Dr. T. Jüstel
LCDs are based on liquid crystals, which rotate
the polarization plane of polarised light by a
rotational angle ά
Polarizer-foil P
Liquid crystal cell (with ITO)
U
Analyzer foil (perpendicular to P)
Pixel on for U = 0
Pixel off for U > 0
6.13 Applications of MH Lamps
Operating principle of a LCD (Liquid Crystal Display)
Chapter High Pressure Discharge Lamps
Slide 29
Incoherent Light Sources
Prof. Dr. T. Jüstel
Requirements for light sources for projectors
• If possible punctual A lot of light from a small volume
• High luminance (light density ) High Hg-pressure
UHP = Ultra High Pressure (Performance)
Approx. 200 bar Hg, electrode separation ~ 1 mm
Strong pressure-broadened lines of Hg
57
7 n
m 40
8 n
m
43
6 n
m
54
6 n
m
400 500 600 700 800
6.14 UHP-Lamps
Chapter High Pressure Discharge Lamps
Slide 30
Incoherent Light Sources
Prof. Dr. T. Jüstel
6.14 UHP-Lamps
Components of UHP-Lamps
Chapter High Pressure Discharge Lamps
Slide 31
Incoherent Light Sources
Prof. Dr. T. Jüstel
Design of UHP-lamps Description of UHP-lamp by
• Chemical equations
Vapor pressure of metal halides
Disintegration of the metal halides in the
plasma
•Temperature distribution in the plasma
Energy balance
Loss via radiation
Loss due to chemical energy
Loss due to heat
Convection (flow) Heat conduction
• Convection equation = Navier-Stokes-Equation
• Energy balance of the electrodes and the wall
6.14 UHP-Lamps
w
uzh:Potential0
y
h
x
h2
2
2
2
Chapter High Pressure Discharge Lamps
Slide 32
Incoherent Light Sources
Prof. Dr. T. Jüstel
6.14 UHP-Lamps
Chapter High Pressure Discharge Lamps
Slide 33
Incoherent Light Sources
Prof. Dr. T. Jüstel
6.15 New Developments
Sulfur lamp: In 1990 the first discharge lamp based on a molecular sulfur
discharge (S4 – S8) was develop
The energy coupling into the discharge takes place by means of a microwave
generator (magnetron), because electrodes can not be used
Chapter High Pressure Discharge Lamps
Slide 34
Incoherent Light Sources
Prof. Dr. T. Jüstel
6.15 New Developments Sulfur lamp: To generate a very large luminous flux
Light source with extremely high light output, about 140000 lm (~ 40 fluorescent
tubes) and (almost) pure-white light (emission band of S8, …. , S2 molecules)
Efficiency: Similar to fluorescent lights (thus 90 - 100 lm/W)
Problems: EMC and lifetime of the microwave generator
Typical operating parameters
Input power: 1.400 W
Ball diameter: approx. 30 mm
Luminous flux: 135000 lm
Color temperature: 5700 K
Starting time: 25 s
Lifetime (lamp): 60.000 h
Lifetime (magnetron): 20.000 h
Light output: 95 lm/W
Chapter High Pressure Discharge Lamps
Slide 35
Incoherent Light Sources
Prof. Dr. T. Jüstel
6.15 New Developments Sulfur lamp: Mechanism of light generation Emission from molecules , e.g. S2
C. W. Johnston, Transport and equilibrium in molecular plasmas: The sulfur lamp,
Technische Universiteit Eindhoven, 2003
Chapter High Pressure Discharge Lamps
Slide 36
Incoherent Light Sources
Prof. Dr. T. Jüstel
6.15 New Developments
Substitution of Hg by Zn (e.g. in automotive headlamps)
Zn-Ar Zn-Ar-metal halide
h 20 lm/W 85 lm/W
Energy efficiency 17% 33%
Ra 0 80
Zn/Ar Discharge Zn/Ar/metal halide Discharge
400 500 600 700 8000,0
0,2
0,4
0,6
0,8
1,0
Ce3+ Luminescence
636
481
472
468
File: Zn discharge lamp (60-75-90W)
Wel = 75 W
LE = 114 lm/W
x = 0.228, y = 0.227
Tc = 34000 K
Efficacy = 20 lm/W
= 0.174 Wopt
/Welektr
Ra8 = 0
Em
issio
n inte
nsity [a.u
.]
Wavelength [nm]
300 400 500 600 700 8000,00
0,05
0,10
0,15
0,20
0,25
0,30
File: Zn discharge lamp (60-75-90W)
Wel = 75 W
LE = 280 lm/W
x = 0.436, y = 0.387
Tc = 3000 K
Efficacy = 85 lm/W
= 0.33 Wopt
/Welektr
Ra8 = 80
Em
issio
n in
ten
sity [a
.u.]
Wavelength [nm]