SNS-RAD-RF-TS-0002.pdf

Document No. SNS-RAD-RF-TS-0002

SNS 805MHz, 5MW Peak Power

Pulsed Klystron

Technical Specification

This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof.

DOCUMENT TITLE

SNS 805 MHz, 5 MW Peak Power Pulsed Klystron Technical Specification

DOC. NO.

SNS-RAD-RF-TS-002

LABORATORY

ORNL / NScD / SNS

DIVISION / GROUP

RAD / EERF, NFDD/Engineering

ISSUE DATE

August 1, 2018

Prepared by:

Moss/Crofford

SIGNATURE / DATE

REV. 2 date REV. 3 date REV. 4 date

Electrical & RF Group Leader

RF Engineer &

TPO:

QA

Representative:

REV.

NO.

REVISION DESCRIPTION

Finalized values for cooling. Revised HV pulse values. Revised lifting fixture description. Updated revision block

Table of Contents

1. General

2. RF Operating Frequency

3. Peak Output Power

4. RF Duty Factor

5. Pulse Repetition Rate

6. DC to RF Efficiency

7. Beam Voltage

8. Beam Current

9. RF Power Gain

10. RF Connectors

11. Instantaneous Bandwidth

12. Collector Power

13. Phase Transfer Characteristic

14. Linearity

15. Output VSWR Tolerance

16. Non-harmonic Noise

17. Harmonic Power

18. Emission Curve

19. Heat Run

20. High Pot Test

21. Altitude

22. X-ray Radiation

23. X-ray Lead Shielding

24. RF Leakage

25. Physical Layout

26. Lifetime and Maintainability

27. Coolant

28. Filament Power

29. Focus Solenoid Power

30. Solenoid Power Supplies

31. Ion Pump

32. Reference Drawing List

Technical Specification For

SNS 805 MHz, 5 MW Peak Power Pulsed Klystrons

SNS – RAD-RF-TS-0002, R01

1. General

This specification establishes the requirements for fabrication and testing of a pulsed cathode klystron for the 805 MHz CCL section of the Spallation Neutron Source (SNS) particle accelerator at Oak Ridge National Laboratory (ORNL). All requirements shall be met without readjusting voltages or retuning. Specific test conditions for each of the requirements are stated where applicable. Note that in addition to the factory acceptance test, the klystron will undergo site acceptance testing and will be required to demonstrate compliance with all specifications on a modulator with a rise time of up to 150 microseconds and the fall time to 20% of the operating voltage of up to 500 microseconds. The flat-top portion of the high-voltage pulse will be up to 1.5 milliseconds long. In addition, there may be a linear tail region of up to 1000 microseconds for the cathode voltage to go to zero.

2. RF Operating Frequency: 805.0 MHz

3. Peak Output Power

a. Peak Output Power: The average of the peak power across the output pulse shall be

5.0 MW at voltage and current described below.

b. Load VSWR: The peak output power requirement shall be verified in the saturated condition and into a load with a maximum 1.05 VSWR at all phases of the reflection.

c. Saturated output power versus cathode voltage: Individual gain curves shall be recorded at 2 kV intervals from 120 kV to 140 kV.

d. Klystron Output: The output circuit shall be designed to be used with standard temperature and pressure conditioned air.

4. RF Duty Factor: 9% minimum

5. Pulse Repetition Rate: 60 Hz

6. DC to RF Efficiency

a. Efficiency: Minimum 55% at full rated power.

b. Efficiency Measurement: Efficiency shall be measured with the calorimetric method.

A comparison with directional coupler measurements shall be provided. The efficiency requirement shall be verified at an output power of 5.0 MW minimum peak power across the width of the pulse.

7. Beam Voltage

a. Beam Voltage: Less than 135 kV at maximum power.

b. Beam Voltage Variation: The klystron shall be able to withstand operation up to 10 kV above the voltage specified in 7a with no degradation in performance.

8. Beam Current: Maximum of 72 amperes.

9. RF Power Gain: 50 dB minimum

10. RF Connectors

a. RF Input: Type N. The Seller shall supply an input circulator and load rated for the required maximum input RF power and shall place connectors at approximately 6” above the top of the HV oil tank flange. Input VSWR shall not exceed 2.0:1 over the full minimum bandwidth at saturation.

b. RF Output: WR-1150 EIA standard flat flange

c. External Loads: If external loads are necessary, utilize air-cooled loads rated for the power coupled out of the cavity. All connections associated with the loads shall be N-type and mounted close to the RF input connectors.

11. Instantaneous Bandwidth

a. Minimum 1 dB instantaneous bandwidth (BW) at saturation: +/- 2.0 MHz

b. Minimum 1 dB instantaneous bandwidth (BW) at 80% of saturation: +/- 1.5 MHz

c. Instantaneous Bandwidth Measurements: The klystron shall be driven at an input power fixed at the level necessary for saturated output power at 805 MHz. For bandwidth at 80% the klystron is driven at an input power fixed at the level necessary for 80% saturated output power at 805 MHz. Record the drive power.

d. Instantaneous Bandwidth Curve: Use a minimum of ten frequency points across the bandwidth

e. Drive at Saturation: Driving the klystron into hard saturation, defined as a greater than 1 dB drop in gain at full power, to broaden the bandwidth shall not be allowed.

12. Collector Power: The collector shall maintain full beam power indefinitely without damage at full pulse width and repetition rate with no RF output. Verification of the collector’s ability to withstand full beam power (no RF output, but full pulsed beam) shall be demonstrated for 24 hours. This requirement is additional to the requirements of section 19, “Heat Run.”

13. Phase Transfer Characteristic

a. Phase Transfer Characteristic Curve: The phase transfer characteristic (insertion phase of the klystron) shall be a smoothly varying, monotonic function as the drive power is varied from 20% to 100 % of saturated drive.

b. Phase Discontinuities: No discontinuities greater than 0.5 degrees are allowed.

14. Linearity

a. Power Transfer Curve: A continuous, smoothly varying, power transfer curve shall be demonstrated for all output powers from 20% of the saturated power to full saturated power.

b. Linearity Departure: The departure of the output power from a best fit straight line shall not exceed 6% of the maximum output power value over a range from 20% to 80% of the nominal output power. The data for the fit shall be taken in 200 kW increments.

15. Output VSWR Tolerance

a. VSWR: 1.2:1

b. Number of Phases: Forward and reflected power shall be measured at six evenly spaced phases of a 1.2:1 mismatch from 0 to 180 degrees.

c. Output Power: The load power shall exceed 80% of the rated power at a minimum of 5 of the 6 phases.

d. Spurious: Any spurious outputs generated by these tests shall be at least 60 dB below the carrier

e. VSWR Measurement: Network analyzer VSWR measurements of the six points shall be provided. This measurement shall be done at a drive corresponding to the full saturated output power for the matched case.

16. Non-harmonic Noise: There shall be no oscillations or discontinuities greater than 60 dB below the nominal carrier with or without RF drive for cathode voltages from 40% of nominal voltage to full rated voltage.

17. Harmonic Power

a. Harmonic Power: Individual harmonics through the 5th shall be a minimum of 27 dB below the carrier for all conditions specified in the non-harmonic noise requirement above

b. Harmonic Power Measurement: The harmonics shall be measured with a standard dual directional waveguide coupler that has been calibrated at harmonics of 805 MHz up to the 5th harmonic. This measurement shall be completed only into a matched load.

18. Emission Curve: Plot a curve showing the percent of nominal cathode current (72 A) with respect to decreasing filament current in 0.25 A steps.

19. Heat Run

a. Number of Trips: The klystron shall be operated for 24 hours at 110% saturated output power with 1.2 mS RF pulses and 1.5 mS high voltage pulses at a 60 Hz repetition rate (average power limited to 500 kW Max), with no more than one klystron trip.

b. Cathode Voltage: The heat run shall be performed at a cathode voltage corresponding to 110% saturated output power.

c. Vacuum Test: At the end of the heat run, after a cool down period of four hours, the klystron shall be disconnected from all vacuum pumping for a period exceeding 14 days. At the end of this period the ion pump shall be energized. The pressure indicated by the pump shall be less than 2x10-7 Torr within 120 seconds.

20. High Pot Test

a. High Pot Test Voltage: The klystron shall withstand a 30 minute high-pot test at 120% of the rated high voltage with no arcs.

b. High Pot Test Curve: A measurement of the high-pot leakage current when connected to the klystron shall be compared to a baseline leakage current when not connected to the klystron.

c. High Pot Test Curve: It shall be plotted in 5 kV intervals between 100 kV and maximum.

21. Altitude: The klystron shall meet all requirements when operated with the internal waveguide pressure at 1000’ above sea level (altitude of ORNL). The seller shall apply appropriate derating factors for testing at different elevations and present those factors to the owner prior during the test reviews.

22. X-ray Radiation

a. X-ray Radiation: The X-radiation at full power output shall be less than 1 mR/hr anywhere within 30 cm of the klystron.

b. X-ray Radiation Measurement: It shall be measured with a NIST certified ionization chamber or equivalent.

23. X-ray Lead Shielding

a. X-ray Lead Shielding: The Seller shall supply all required shielding materials. The shielding support shall be designed such that the lead is not part of the structural support. The shielding shall be designed to be removed around external interface points, such as pipe flanges and RF connections, without the need to disconnect those interface points.

b. Lead Panel Weight: No single lead panel shall exceed 30 pounds. This limit also applies to the support structure elements.

24. RF Leakage: RF Leakage from the klystron shall not exceed 0.2 mW/cm2 at a distance of 30 cm when operating at maximum peak power and duty cycle.

25. Physical Layout

a. Physical Drawings: Please see the attached reference drawings for the intended physical layout.

b. Operating Position: The klystron shall be operated in the vertical position, cathode end down in an HV oil tank.

c. Output Waveguide Flange Position: The output connection shall be shall be placed at 96” above the top of the HV oil tank. The top of the HV oil tank is approximately 38” above the finished floor. Details are shown in the attached reference drawings.

d. Lifting Devices and Points: Design and provide a lifting device and lifting point on the klystron in accordance with ASME BTH-1-2017, “Design of Below the Hook Lifting Devices”. Provide design calculations certifying that the lifting device and lift points can lift the klystron with a safety factor of 2.0. List the sections of the ASME code applicable to the device design as part of the design package. Test the lifting device with a load

1.25 times larger than the design load and provide the results. Provide engineering plans for fabrication of additional lifting fixtures by SNS. All fixtures shall be labeled with capacity.

e. Lifting: The klystron and solenoid shall be capable of being lifted as a single unit or individually. The klystron and solenoid shall hang vertically from the lifting fixture as a unit or individually. The seller shall provide alignment pins to assist in placing the solenoid and klystron on the owner’s oil tank.

f. Klystron Tank Flange Hole Pattern: The existing hole pattern shown in the drawing 153Y645178-A shall be utilized.

g. Overall Height: The top of the klystron to include shielding shall not exceed 133” above the HV tank.

h. Output Window: The klystron shall have a single output connection port. Beryllium oxide shall not be used. Provide a port with a 9MM SMA fitting for connecting an arc sensing fiber. The port shall be oriented such that it views the output window and located to ensure adequate clearance for the fiber bend radius. The output window may be cooled with air, water or a combination of both. It water cooled, the window water shall be supplied on the body cooling circuit. The maximum airflow for window cooling shall be 100CFM with an input air temperature of 90 degrees F at 70% humidity. The air connecter shall be a single, unthreaded pipe with a three-inch outer diameter. Air blowers are existing Cincinnati Fan model PB-10A

i. Cathode Socket: Provide a socket for the cathode high voltage and filament (heater) connections. The socket will mount inside of the klystron HV oil tank. Provide 0.25-inch diameter stud-type terminals for the cathode and cathode-heater cable connections.

These cables are existing and use ring lugs.

26. Lifetime and Maintainability

a. Design Lifetime: The design lifetime shall be 100,000 hours. The design lifetime shall be demonstrated by analysis and presented at the first review.

b. Maintainability: The structure and shielding of the klystron shall be designed for ease of dismantling and repair. The klystron shall be capable of being separated from the focus solenoid.

27. Coolant

a. Coolant Channels: Cooling channels shall be constructed with copper tubing. Cooling design shall be presented as part of the review process. Fitting and union type, location, and quantity shall be approved by the Company prior to fabrication.

b. Water Resistivity: The klystron shall be cooled with de-ionized water having a resistivity of between 1 and 2 Meg-Ohm-cm

c. Coolant Flow: The total coolant flow required, including the klystron body, collectors, and solenoid, shall be less than 150 GPM in normal operation (135 kV, 72 A, 5.0 MW peak power, 9% duty cycle). The total flow may be increased for the heat run.

d. Pressure Drop: The total pressure drop at normal operating flows shall not exceed the following, +/- 5 %:

Collector: 5 PSIG at 140 GPM

Body: 45 PSIG at 5 GPM

Solenoid: 45 PSIG at 5 GPM

e. Static Pressure Test: The coolant courses shall withstand a static test pressure of 200 PSIG at any coolant port for 1 hour with no loss of pressure

f. Water Inlet Pressure: Normal operating inlet pressure will be 90 PSIG, +/- 5%

g. Water Inlet Temperature: The klystron cooling water inlet temperature nominal set point is 92 degrees F, +/- 5%.

h. Water Outlet Pressure: The return pressure shall be a maximum of 30 PSIG, +/- 5%.

i. Cooling Connections: All external cooling connections to be 304L SS with ANSI class 150RF flanges. The klystron body and solenoid connections shall be 1.5” and the collector shall be 3.0” at the tie-in points. Place the tie-in points at the location shown in the reference drawings

j. Number of cooling circuits: Maximum of three. One for the klystron body, one for the solenoid and one for the collector. The maximum flow in the klystron body and solenoid cooling circuits shall be 5 GPM. The maximum flow in the collector shall be 140 GPM

k. Local Temperature Measurement: Provide a means thermal well mounted RTDs to locally measure the inlet and outlet water temperatures for the klystron body, output window, solenoid, and collector cooling circuits. Place labelled female connections for each device at the location of the RF connectors and provide mating plugs for use by the Company.

28. Filament Power

a. Heater Current: The filaments shall be AC powered and draw less than 35 A.

b. Heater Voltage: at less than 35 V.

c. Filament Power: The filaments shall be wired for minimal 60 Hz gain variation. The gain variation, with respect to the phase of the AC mains shall not exceed 0.05dB and it shall be measured in 1millisecond steps over the AC mains voltage cycle.

29. Focus Solenoid Power

a. Main Coil Voltage: The solenoid voltage shall be less than 150 V.

b. Main Coil Current: The solenoid current shall be less than 40 A.

c. Main coil Power: The main focus coil shall consume less than 3.5 kW.

d. Auxiliary Focus Coil Voltage: The auxiliary focus coil shall operate at a voltage below

100V.

e. Auxiliary Focus Coil Current: The solenoid current shall be less than 30 A.

f. Auxiliary Focus Coil Power: The auxiliary focus coil shall consume less than 500 W.

30. Solenoid Power Supplies: Two or fewer solenoid power supplies shall be used.

31. Ion Pump

a. Number of Ion Pumps: Two ion pumps shall be used. Only one will be necessary for normal operation. The second is spare.

b. Type of ion pump: The ion pumps shall be Varian.

c. Ion Pump Connector: Each will use the LEMO ERA.35.415.FPA connector

32. Reference Drawing List

a. 153Y645178-A – “Spallation Neutron Source Standard Klystron Receptacle Detail”

b. 104010108-E8U-8300-A005 – “RF Power Systems 5 MW Klystron Interface Location”