6. High Pressure Discharge Lamps - fh-muenster.de · Chapter High Pressure Discharge Lamps Slide 1 Incoherent Light Sources Prof. Dr. T. Jüstel 6. High Pressure Discharge Lamps Content

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


Slide 2



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)


Slide 3



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


Slide 4



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


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


Slide 5




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)


Slide 6



Evacuated outer bulb

Burner (Hg, noble gas = starting

Gas, mostly Xe)

Ballast

6.3 The High-Pressure Mercury Lamp (HP)

Electrode

Melting


Slide 7



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


400 500 600 700 800

0

1

2

3

4

5

Inte

nsity [

a.u

.]

Wavelength [nm]


Slide 8



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


400 500 600 700 800

0

1

2

3

4

5

Phosphor

Plasma

Re

lative

In

ten

sity [

a.u

.]

Wavelength [nm]


Slide 9



Sn2+ or Mn4+ phosphors

as UV Red converter

Problem: Low lumen equivalent of these phosphors


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]


Slide 10



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


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


Slide 11



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


Slide 12



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


Slide 13



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


Slide 14



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


Slide 15




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


Slide 16



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


20 mm

Polycrystalline structure

Crystal


Slide 17



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)



Slide 18



Architectural and street lighting

6.10 Application of HPS Lamps


Slide 19



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


Slide 20



589 nm

(Na)

451 nm

(In)

535 nm

(Tl)

HPI (High Pressure Iodide) lamps



Slide 21



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


Spectrum of a MH lamp


Slide 22



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, ...)



Slide 23



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


Slide 24



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)



Slide 25



SSTV market = Stage-Studio-TV

Reflector

Spherical

mirror f

Fresnel-lens

Farbtemperatur = 5600 K



Slide 26



In the „beamer“



Slide 27



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



Slide 28



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


Operating principle of a LCD (Liquid Crystal Display)


Slide 29



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


Slide 30



6.14 UHP-Lamps

Components of UHP-Lamps


Slide 31



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


Slide 32



6.14 UHP-Lamps


Slide 33




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


Slide 34



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


Slide 35



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


Slide 36




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]

Documents

6. High Pressure Discharge Lamps - fh-muenster.de · Chapter High Pressure Discharge Lamps Slide 1 Incoherent Light Sources Prof. Dr. T. Jüstel 6. High Pressure Discharge Lamps Content