Specs and Drawings_Electron gun.pdf

Electron Gun Specification for Quote Request

21 Aug 2026

U.S. Naval Research Laboratory

1. Background

a. The Naval Research Laboratory (NRL) requires a thermionic electron gun producing two round electron beams of 1.0 A each at 20 kV, designed to be transported by an external solenoid magnet in a shielded-cathode configuration, manufactured to a custom electrode geometry and pole piece design provided by NRL.

b. The anode electrode will be integral to a magnetic pole piece of vanadium permendur material with custom features for attachment to an NRL tube assembly; the electron gun assembly delivered by the vendor will include the pole piece/anode assembly.

i. Reference attached drawings: NRL gun-anode assy.pdf, NRL anode pole piece.pdf

c. The method used by the vendor to attach the electron gun to the anode pole piece must ensure precision transverse and rotational (clocking) alignment of the two cathodes to the beam holes in the mod-anode and the anode, and precision axial distance between the cathodes and the anode.

d. Precision mechanical alignment features on the anode pole piece will be used to ensure the correct transverse and rotational alignment of the two anode beam holes to the NRL tube RF circuit beam tunnels, downstream of the electron gun.

i. Reference attached drawing: NRL gun-anode assy.pdf, NRL anode pole piece.pdf

e. The vendor will perform the mechanical, electrical (high voltage standoff, surface field stresses), and thermo-mechanical design necessary to produce the electron gun with the specified performance matching the provided custom electrode geometry at operating temperature nominally 950-1250 °C.

f. The vendor will perform final heat treatment of the anode pole piece assembly for critical magnetic properties, after necessary braze operations are complete; material and heat treatment procedure for vanadium permendur as described in drawing.

i. Reference attached drawing: NRL anode pole piece.pdf

g. The vendor will perform hi-pot testing of the finished gun assemblies to ensure the electrical insulation (ceramics, cables, potting materials) can withstand the high operating voltages in air at atmospheric pressure.

2. Electrode schematic, nominal

3. Electrode geometry and critical tolerances

a. The custom electrode geometry is shown in the attached drawing. Detailed

3D models with final dimensions for production will be provided upon completion of a purchase order contract.

b. Critical tolerances

i. Cathode-FE gap: +/- 0.02 mm tolerance

ii. Cathode-FE axial spacing: +/- 0.002 mm

iii. The corner radius of the cathode edge should be the minimum reasonably achievable.

iv. Cathode to mod-anode axial spacing: +/- 0.012 mm

v. Mod-anode opening ID: +/- 0.012 mm

vi. Mod-anode opening profile curvature radii: controlled radius

vii. Anode opening profile curvature radius: controlled radius

viii. Cathode-anode spacing: +/- 0.012 mm

ix. Surface finish of vanadium permendur anode pole piece area near gun electrodes including fillets and holes: 0.0002 mm Ra

1. Requiring specialized machining and surface finishing techniques

c. Vendor will provide NRL with estimate of attainable tolerances in the range

950-1250 deg C.

d. Assembly must withstand excursion during vacuum bakeout to 450 deg C for

24 hrs and return to within tolerances.

e. Reference attached drawings: NRL gun electrodes.pdf, NRL gun-anode assy.pdf, NRL anode pole piece.pdf

4. Operating voltages, nominal

a. V anode = 0V

b. V cathode wrt anode = -20kV

c. V mod. Anode (MA) wrt cathode (range) = Max: +5785 V (at 950 ° C), Min:

+4765 V (at °1250 C)

d. V focus electrode (FE) wrt cathode = 0 V to -100 V

5. Operating beam current

a. 1.0 A per beam, 2x electron beams

6. Operating method

a. The electron gun will be operated by an external power supply in a cathode-pulsed mode, such that the cathode voltage and mod-anode voltage are held at a constant ratio and the beam is turned on and off by pulsing the cathode from 0 V to -20 kV.

7. Cathode

a. MM/M type, or other best suitable for producing current density average over emitting surface up to 8 A/cm^2, and up to 30 A/cm^2 in local spots, with nominal operating temperature in the range 950-1250 °C.

8. Transverse dimension requirement

a. The entire gun assembly, including high-voltage wire connection taps and any external features, must fit within a 1.890 inch diameter hole, for clearance when inserting into the magnet.

b. Reference attached drawing: NRL gun-magnet clearance.pdf

9. Longitudinal dimension requirement

a. The wire taps for the cathode, filaments, and mod anode must be positioned far enough longitudinally from the anode pole piece to prevent voltage breakdown in air at 20 kV, 50 mm or farther.

R0.8016x

R35 .50

R0.80

11.25°

Critical alignment feature (2x pin holes)

16x holes for venting;

Tolerance not critical.

CR: Controlled precision radius

Precision slip fit

Material: Vanadium Permendur (Fe 49%/Co 49%/V 2% by wt) Trade names Hiperco 50A, Vacoflux 50

.0008

45°

A

A

4x threaded holes

1.00 5.00

8.

.0

±0

.2

±0

K

SECTION A-A

SCALE 2 : 1

16x hole fillets (rounds) for purpose of smoothing edge; Fillet radius size not critical, but must smoothly transition to surface contour.

Vendor choose weld ring material for optimal CTE match with vanadium permendur pole piece

.0002

CR0.30

DETAIL K

SCALE 6 : 1Notes:

Surface finish treatment of Vanadium Permendur as required to achieve 0.2 • micron Ra finish on machined anode surfaces and holes near gun electrodes:

Example process: Rough machining including hole fillet geometry > • Precision hole finishing > Surface smoothing including electropolishing.

After machining, final heat treatment of Vanadium Permendur for critical • magnetic properties:

Heat to 885 °C +/- 15 °C in dry hydrogen or high vacuum atmosphere • for 2-4 hrs. Do not exceed 900 °C.

Cool at rate of 100-200 °C/hr until below 370 °C.•

Surface, hole fillets, hole interior

A A

B B

Anode Pole Piece assy

DO NOT SCALE DRAWING

Prelim

SHEET 1 OF 1

6/18/2026A. Cook

UNLESS OTHERWISE SPECIFIED:

SCALE WEIGHT:

REVDWG. NO.

B

SIZE

TITLE:

NAME DATE

COMMENTS:

Q.A.

MFG APPR.

ENG APPR.

CHECKED

DRAWN

FINISH

MATERIAL

INTERPRET GEOMETRIC

TOLERANCING PER:

DIMENSIONS ARE IN MILLIMETERS

TOLERANCES:

FRACTIONAL

ANGULAR: MACH BEND

TWO PLACE DECIMAL

THREE PLACE DECIMAL

APPLICATION

USED ONNEXT ASSY

PROPRIETARY AND CONFIDENTIAL

THE INFORMATION CONTAINED IN THIS

DRAWING IS THE SOLE PROPERTY OF

<INSERT COMPANY NAME HERE>. ANY

REPRODUCTION IN PART OR AS A WHOLE

WITHOUT THE WRITTEN PERMISSION OF

<INSERT COMPANY NAME HERE> IS

PROHIBITED.

U.S. Naval Research Laboratory Washington, DC

A

R4.50

0.

2.

2.47 ±0.012

.7

±0

.2

±0

B

C

SECTION A-A

SCALE 5 : 1

CR 0.05

.0

±0

.0

DETAIL B

SCALE 100 : 1

CR 0.02

0.30

CR 0.05

0.30

CR 0.10

DETAIL C

SCALE 30 : 1

Mod-Anode profile

Cathode-FE spacing

CR: Precision controlled radii

Spherical cathode radius

A A

B B

Gun Electrodes

DO NOT SCALE DRAWING

Prelim

SHEET 1 OF 1

6/1/2026A. Cook

UNLESS OTHERWISE SPECIFIED:

SCALE: WEIGHT:

REVDWG. NO.

B

SIZE

TITLE:

NAME DATE

COMMENTS:

Q.A.

MFG APPR.

ENG APPR.

CHECKED

DRAWN

FINISH

MATERIAL

INTERPRET GEOMETRIC

TOLERANCING PER:

DIMENSIONS ARE IN MILLIMETERS

TOLERANCES:

FRACTIONAL

ANGULAR: MACH BEND

TWO PLACE DECIMAL

THREE PLACE DECIMAL

APPLICATION

USED ONNEXT ASSY

PROPRIETARY AND CONFIDENTIAL

THE INFORMATION CONTAINED IN THIS

DRAWING IS THE SOLE PROPERTY OF

<INSERT COMPANY NAME HERE>. ANY

REPRODUCTION IN PART OR AS A WHOLE

WITHOUT THE WRITTEN PERMISSION OF

<INSERT COMPANY NAME HERE> IS

PROHIBITED.

U.S. Naval Research Laboratory Washington, DC

.0

.2

±0

SECTION A-A

SCALE 3 : 1

Gun-side weld ring attach in this area as convenient

Vendor choose weld ring material for optimal CTE match with vanadium permendur pole piece

These lengths and terminations at vendor discretion

5.47 ±0.012

DETAIL B

SCALE 8 : 1

Model shows gun and anode • electrode positions in final assembly as delivered by vendor.

Gun-side weld ring mate of gun to • anode sets critical cathode-anode separation.

Alignment features required to set • clocking/rotational alignment of cathodes to anode holes to high precision.

Exact design of gun-side weld ring • location and alignment method is at vendor discretion, and is not shown.

A A

B B

Prelim

DO NOT SCALE DRAWING SHEET 1 OF 1

6/17/2026 U.S. Naval Research Laboratory

Washington, DC

UNLESS OTHERWISE SPECIFIED:

SCALE: WEIGHT:

REVDWG. NO.

B

SIZE

TITLE:

NAME DATE

COMMENTS:

Q.A.

MFG APPR.

ENG APPR.

CHECKED

DRAWN

FINISH

MATERIAL

INTERPRET GEOMETRIC

TOLERANCING PER:

DIMENSIONS ARE IN MILLIMETERS

TOLERANCES:

FRACTIONAL

ANGULAR: MACH BEND

TWO PLACE DECIMAL

THREE PLACE DECIMAL

APPLICATION

USED ONNEXT ASSY

PROPRIETARY AND CONFIDENTIAL

THE INFORMATION CONTAINED IN THIS

DRAWING IS THE SOLE PROPERTY OF

<INSERT COMPANY NAME HERE>. ANY

REPRODUCTION IN PART OR AS A WHOLE

WITHOUT THE WRITTEN PERMISSION OF

<INSERT COMPANY NAME HERE> IS

PROHIBITED.

Gun-anode assy

A. Cook

C

SECTION B-B

SCALE 1 : 1.5

Magnet end plate

.8

DETAIL C

SCALE 3 : 1

Anode pole piece

Entire gun assy with weld ring and electrical connections must fit through this ID, inserted from right-hand-side of drawing, with anode pole piece seated as shown.

A A

B B

Gun-magnet clearance

DO NOT SCALE DRAWING

Prelim

SHEET 1 OF 1

6/2/2026

U.S. Naval Research Laboratory Washington, DC

UNLESS OTHERWISE SPECIFIED:

SCALE WEIGHT:

REVDWG. NO.

B

SIZE

TITLE:

NAME DATE

COMMENTS:

Q.A.

MFG APPR.

ENG APPR.

CHECKED

DRAWN

FINISH

MATERIAL

INTERPRET GEOMETRIC

TOLERANCING PER:

DIMENSIONS ARE IN MILLIMETERS

TOLERANCES:

FRACTIONAL

ANGULAR: MACH BEND

TWO PLACE DECIMAL

THREE PLACE DECIMAL

APPLICATION

USED ONNEXT ASSY

PROPRIETARY AND CONFIDENTIAL

THE INFORMATION CONTAINED IN THIS

DRAWING IS THE SOLE PROPERTY OF

<INSERT COMPANY NAME HERE>. ANY

REPRODUCTION IN PART OR AS A WHOLE

WITHOUT THE WRITTEN PERMISSION OF

<INSERT COMPANY NAME HERE> IS

PROHIBITED.

A. Cook