experimental progress in 2003 of the uw iec facility · rpa 1 experimental progress in 2003 of the...

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Experimental Progress in 2003 of the UW IEC Facility

6th U.S.-Japan IEC WorkshopTokyo, Japan

October 20-21, 2003

R. P. Ashley and the UW IEC Team

University of Wisconsin-Madison, Fusion Technology Institute1500 Engineering Drive

Madison WI 53706(608) 265-3098

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Overview of Activities

• Operation to 180 kV• Produced 180 million neutrons per second steady state• Fabricated internal and external activation systems• Studied 3He ion damage of tungsten grid wire• Upgraded diagnostics with the addition of a pyrometer,

spectrometer, and off axis proton detector• Designed a standardized cathode grid fabrication system• Conducted thermionic electron emission studies• Developed and constructed a helicon source ion gun

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We Have Produced a UW IEC Record of 1.8 x 108 D-D Neutrons /s

1.E+06

1.E+07

1.E+08

1.E+09

Jan-98

Jan-99

Jan-00

Jan-01

Jan-02

Jan-03

Jan-04

Date Experiments Conducted in Wisconsin IEC Device

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We Have Operated at a Maximumof 180 kV D-D

Maximum Voltage vs. Time

0

20

40

60

80

100

120

140

160

180

200

Sep-99

Dec-99

Mar-00

Jun-00

Sep-00

Dec-00

Mar-01

Jun-01

Sep-01

Dec-01

Mar-02

Jun-02

Sep-02

Dec-02

Date

D-3HeD-D

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University of Wisconsin IEC Facility

High Voltage Feedthru

Typical operating conditionsCathode voltage:40-150 kVCathode current: 30-60 mAPressure:1.5-2.5 mTorr

450 l/s Turbo Pump

91cm

65cmOuter grid anode:50cm diameter SS

Inner grid cathode:10cm diameter SS

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Primary Diagnostics

Silicon charged particleon axis proton detector

1200 mm2

3He Neutron Detector

Video camera

Grid Temperature

Pyrometer

VoltageCurrent

PressureChamber Temp

LabView Data Loggercomputer

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Off Axis Detector Confirms SignificantVolume Source of D-D Protons

Silicon charged particle detector 450 mm2

There are three main regions of fusion reactionsin the UW IEC reactor

1. converged core region2. 3He embedded fusion3. volume source region

• Off axis detector shows similar D-D proton rates per unit volume as the on axis detector, confirming a volume source of D-D protons

• Off axis detector shows negligible D-3He proton rates per unit volume confirming embedded D-3He fusion

12

3

3

3

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Gamma Detector

Ion ExchangeResin

13N Production Has Been Accomplished with Water Cooled Cathode Target

Heat Exchanger

1. Embedded 3He fusion occurs in the stainless steel tube cathode2. 13N is produced in the cathode tube cooling water

Stainless steel tube cathode

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13N Production Also Accomplished with Internal Water Circulator

Gamma Detector

Ion ExchangeResin

Heat ExchangerWater pump

1. Stainless steel tube assembly is exposed to D-3He fusion proton flux2. 14 MeV protons penetrate the tubes and activate the oxygen in H2O3. 13N is captured in the ion exchange resin

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• Thermionic emission reduces the overall fusion rate at fixed meter current

Diagwire experiments help determine ion flow characteristics *

• Wire power balance helps diagnose ion flux patterns

*details will be reported at next workshop

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Fast He Ions Can Produce Significant Damage in Tungsten

Wire grid cathode was replaced by a1 cm square tungsten sample target

5 µm

SEM picture of sample before

operation

sample after 6 x 1018

helium ions /cm2

5 µm

sample after2 x 1019

deuterium ions /cm2

25 µm

D+, 20 kV, 5 mA2 mtorr, 1100 °C

1 CM

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Fabrication System for Standardized Grid

2. Wax poured into mold

4. Wires spot welded at junctions 5. Wax form melted away@100C

6. Finished grid cathode

1. Mold produced fromrapid prototype model

10 cm

3. Wires wound around wax form

10 cm

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Ion Gun on New Chamber(see talk by Piefer)

IEC Chamber

Ion source

Source Turbo pump

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Future Plans

• Improve proton rates for medical isotope production• Study converged core formation with new ion source• Understand grid wire damage caused by helium ions• Characterize ion and impurity population densities

with spectroscopy studies• Simulate ion flow to better understand the source

regions and reaction rates

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At 100 kV, We Have Seen Lower Rates of D-D Neutrons at Lower Pressures

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Gamma detector is all-in-one instrument for ease of use

Scintillation headPhoto multiplierTube

Powered by USB cable

Preamp, multi-channel analyzer and HV power supply contained in base

ORTEC model 950-4 Gamma detector with MicrobaseTM

Specs:

Laptop displays data in real time