IEC Fusion Reactor Mark 3 Ion Collector Array

Overview:

A segmemted ion collector is added to the fusor grid to allow measurement of ion bombardment intensity vs position. Ion collector was machined out of a copper shim on a 5-axis CNC mill

Rough estimate for thermal resistance of copper standoffs on ion collector: Aat 16mTorr and 13k, ~5ma of current will be drawn from the grid power supply yielding 65W total into the grid (assuming 100% electrical power disipated into grid). The 3 ring grid will have 12 segments, so 5.4W/segment. With a 10 element ion collector array mounted onto a given segment, 0.54w/collector.

Assuming equal power dissipation into each collector, for a 25C temperature rise for wach collector the standoff should have ~50C/W thermal resistance. Assuming thermal conductivity for copper K=400 w*m^-1*k^-1, a 1/16"(2.5mm) wide, 1/16"(2.5mm) long standoff should have a 0.05mm thickness.

The final design had a 0.2mm thickness with a 0.028"(1.1mm) hole (#70 drill) drilled through the width-length plane.

Ion Collector (9/19/2014)

Copper shim mounted on holder in a-axis chuck, b-axis rotated 90 degrees, milling observation hole through thickness

Ion Collector (9/19/2014)

Copper shim mounted on holder in a-axis chuck, b-axis rotated 90 degrees, milling observation hole through thickness

Ion Collector (9/19/2014)

Copper shim mounted on holder in a-axis chuck, b-axis rotated 90 degrees, milling observation hole through thickness

Ion Collector (9/19/2014)

Notch milled in front of face, using slotting saw to mill out collector segments. Slot is 0.01" thick.

Ion Collector (9/19/2014)

Notch milled in front of face, using slotting saw to mill out collector segments. Slot is 0.01" thick.

Ion Collector (9/19/2014)

Several collector segments milled out

Ion Collector (9/19/2014)

Several collector segments milled out

Ion Collector (9/19/2014)

All collector segments milled out

Ion Collector (9/19/2014)

All collector segments milled out

Ion Collector (9/19/2014)

All collector segments milled out

Ion Collector (9/19/2014)

All collector segments milled out, mounted in a-axis holder

Ion Collector (9/19/2014)

Milling slot in other face leaving ~0.02mm thickness on the standoffs.

Ion Collector (9/19/2014)

Milling slot in other face leaving ~0.02mm thickness on the standoffs.

Ion Collector (9/19/2014)

Milling slot in other face leaving ~0.02mm thickness on the standoffs.

Ion Collector (9/19/2014)

Cutting collector arrays apart

Ion Collector (9/19/2014)

Arays were acid etched in brite dip to remove burs. Ion collector arrays on quarter for scale.

Ion Collector (9/19/2014)

Ion collector arrays on BNC fitting for scale.

Ion Collector (9/19/2014)

Angled view of collector

Ion Collector (9/19/2014)

View showing standoff thickness

Ion Collector (9/19/2014)

Test fit on test grid

Ion Collector (9/19/2014)

Test fit on test grid

Ion Collector (9/19/2014)

Holes drilled in segmant face for increaced thermal resistance, ion collectors mounted on fusor grid.

Ion Collector (9/19/2014)

Holes drilled in segmant face for increaced thermal resistance, ion collectors mounted on fusor grid.

Ion Collector (9/19/2014)

Grid mounted on fusor.

Ion Collector (9/19/2014)

Grid HV off

Ion Collector (9/19/2014)

Grid HV on

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