high power helicon (hph) - university of...

High Power Helicon (HPH)J. Prager*; T. Ziemba; R. Winglee; J. Slough; J. Carscadden

*Department of Earth and Space SciencesUniversity of WashingtonSeattle, WA 98195-1310

jprager@u.washington.edu

- 14 Isolated Gate Bipolar Transistors (IGBTs) in parallel- IGBT rating: 250 A and 1200 V- Peak Antenna currents > 2 kA- Frequency range: 0.3 - 1.1 MHz- Standard Operation: 600 kHz- Charging Capacity: 7.9 mF- Shot length: 35 - 400 µs

Antenna Current

-2000

-1000

0

1000

2000

-50.00 0.00 50.00 100.00 150.00 200.00time (us)

Curre

nt (A

)

- m = +1 antenna- diameter = 7 cm- length = 15 cm- Six magnets produce DC field (typical: 130, 260, 390 G)- Gas: H, He, N, Ar, Xe, Ne (Ar typical)- Plasma accelerated in downstream direction only

HPH Source

HPH Power Supply

DC Magnetic field

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

-0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Int. Langmuir Face Planar Midstream Planar

DownstreamPlanar

RFA

Magnetic Field - Side View

Magnetic Field - Top View

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

-0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Impacts Side of ChamberConnects to Ambient Earth Magnetic Field

On Axis Magnetic Field (Axial Direction)

0.01

0.1

1

10

100

1000

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8Distance (meters)

Mag

net

ic F

ield

(G

)

390 Gauss260 Gauss130 Gauss

Face Planar Midstream Planar cm

DownstreamPlanar

RFA

Power Deposition Data

Radial Planar Probe Data

Face Planar Peak Density

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

-4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0Distance (cm)

Prob

e C

urre

nt

130 Gauss260 Gauss390 Gauss

Midstream Radial Profile

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

-5.0 0.0 5.0 10.0 15.0 20.0 25.0Distance (cm)

Prob

e C

urre

nt

130 Gauss260 Gauss390 Gauss

Boron nitride cover and back plateTungsten stinger

Tungsten ion collector

- Distribution peaked on axis- FWHM decreases with field strength

Future WorkFuture Work- Measure thrust of HPH on a thrust stand- Measure power and downstream properties in dual coil mode- Design gas feed for more efficient gas handling in DC or amplitude modulated operation- Continue optimization and performance characterization- Test and characterize pre-ionizer-Study downstream magnetic properties

- Measure thrust of HPH on a thrust stand- Measure power and downstream properties in dual coil mode- Design gas feed for more efficient gas handling in DC or amplitude modulated operation- Continue optimization and performance characterization- Test and characterize pre-ionizer-Study downstream magnetic properties

This presentation includes contributions from Race Roberson, Nathan Stobie, Gregory Quetin, and Joni DeBoever

This presentation includes contributions from Race Roberson, Nathan Stobie, Gregory Quetin, and Joni DeBoever

100 us

-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.0 20.0 40.0 60.0 80.0 100.0

Discriminator Voltage

Non

-nor

mal

ized

Ene

rgy

Dis

trib

utio

n

115 us

-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.0 20.0 40.0 60.0 80.0 100.0

Discriminator Voltage

Non

-nor

mal

ized

Ene

rgy

Dis

trib

utio

n

130 us

-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.0 20.0 40.0 60.0 80.0 100.0

Discriminator Voltage

Non

-nor

mal

ized

Ene

rgy

Dis

trib

utio

n

145 us

-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.0 20.0 40.0 60.0 80.0 100.0

Discriminator Voltage

Non

-nor

mal

ized

Ene

rgy

Dis

trib

utio

n

160 us

-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.0 20.0 40.0 60.0 80.0 100.0

Discriminator Voltage

Non

-nor

mal

ized

Ene

rgy

Dis

trib

utio

n

175 us

-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.0 20.0 40.0 60.0 80.0 100.0

Discriminator Voltage

Non

-nor

mal

ized

Ene

rgy

Dis

trib

utio

n

Retarding Field Analyzer (RFA) Data

- Data at 390 G & 75 kW peak power- Dual peak energy distribution- Average energy = 35 eV (for Ar)

- 5 nickel grids (55% transparency)- 24.9 mm x 19.5 mm x12 mm- Orafice 2.6 mm in diameter

Peak Power

0

20

40

60

80

100

120

100 150 200 250 300 350 400 450 500 550Charging Voltage (V)

Peak

Pow

er (k

W)

130 G260 G390 G

Peak Power vs. Field

0

20

40

60

80

100

120

0 50 100 150 200 250 300 350 400 450Magnetic Field (gauss)

Inpu

t Pow

er (K

W)

400 V450 V500 V425 V475 V

Source Plasma Density

0

1

2

3

4

5

6

0 20 40 60 80 100 120Peak Power (kW)

Peak

Den

sity

(x 1

020 m

-3)

130 G260 G390 G

Isp Measurement: Time of Flight (130 G)

0

500

1000

1500

2000

2500

3000

3500

4000

0 10 20 30 40 50 60 70 80Power (kW)

Isp

(sec

)

- Input power is calculated from a direct measurement of the antenna current and voltage- 100 kW peak power deposition into the plasma- Source density > 1020 m-3

- Isp increases with increasing power; no saturation has been observed- Input power scales with base magentic field strength- Source density saturates as power increases

Charging CapIGBT Switch

Gate Switch

Antenna Tuning Caps

Plasma

DumpResistor

Charging Supply

SnubbingCircuit

HPH Power Supply

RFA Probe Current: Time Profile

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

-100 0 100 200 300 400

Time (us)

Prob

e C

urre

nt 0 V18 V36 V54 V70 V