SLAC Project-X RF Development FY12 SOW March

Board level amplifier research Finish in-progress experiments and fully-document the results. Demonstrate efficiency (>60%) and phase stability of recently developed amplifiers/modules.

Transistors/Amplifiers MRFE6VP5600H: 600W 60% efficiency (50V drain) and a Rth JC of 0.12°C/W BLF888B: –Up to 600W 50V drain with 66% drain efficiency and about 21dB gain. 48V with 71% drain efficiency and little over 21dB gain.

650MHz (Nautel/NXP)

Others –NXP BLF888B test fixture: second and third harmonics were measured at -50dBc.

IIFC – BARC 325MHz Three prototypes: FR4, PTFE (RT5880) and TC350 Combining two FR4 boards to get to 1kW, assembly in-progress, 19” rack, 6U. The PTFE and TC 350 prototypes get up to 1kW and 800W respectively. Drain efficiency of baseline module is in the 63% to 69%. Gain of baseline module 19.8dB to 22.2dB

IIFC – RRCAT 650MHz Indus-2 using 2 x 505MHz Each 15kW consists of 2-8kW towers (euro rack) Indus-2 based on 320W modules with efficiency in the 650MHz, 200W module built and tested ~11dB gain. Moving towards 350W at 50V drain using a different device… this is a study in progress, no prototype.

IIFC – RRCAT 650MHz At kW levels power radial combiners built: –2kW 8-way combiners at 352, and 704 MHz –4kW 16-way unit at 352 MHz –15kW 2-way combiner at 650 MHz Rigid coaxial combiners (silver coated brass): –16 way 4kW: 1 5/8” output –2 way 20kW: 3 1/8” output –2 way 40kW: 6 1/8” output

IIFC – RRCAT 650MHz Couplers (silver coated brass): –1 kW 70 mm long. –4 kW coupler is 200mm –20 kW is 320 mm long. Others: –Coax transitions. –Dummy loads.

Evaluate already-purchased 2.5 kW vendor-built sub-unit Purchased 2.5kW unit from Nautel which will be received by the end of August. On track…. Acceptance testing to ensure the specifications are achieved. Standard 19” rack, 3U (target) Power supply performance. Selection of a >95% efficiency supply for the dynamic range specified. At 30kW a different power distribution is required to improve performance.

Efficiency assessment for a ~3.16kW RF output –Transistors: 70% –Output losses: 0.32dB –Required power from FA, IPA and driver PS (DC): ~4950W –PS efficiency (AC-DC): 95% –AC required for FA: ~5220W (including controls) –AC-RF efficiency: 3.16kW

Class F amp control, packaging, powering, and performance SLAC will interface with Green Mountain to investigate the issues associated with DC-bus regulation and bandwidth requirements as well as a control scheme to provide phase and amplitude control, and the cooling required. A control loop will be defined from which the estimated performance characteristics will be derived. SLAC will investigate issues associated with integrating the Green Mountain amplifiers into the overall system. The assumption is that appropriate information will be shared with SLAC such that an independent development is not necessary.

325MHz & 650MHz –325MHz tests are completed, 85.8% drain 120W. –First 650MHz prototype testing is in progress, initial results show 80% drain 120W. –Combine 5 x 120W (operating at ~100W) to a 500W module.

Combining Networks –Trade-off study on various methods to combine RF power sub-units. –Investigate cost vs efficiency as well as packaging complexity. –Outcome will be a survey of the present state of the art and identification of potential avenues of development. –A detailed plan will be developed to experimentally evaluate new schemes

650MHz Combining up to few kW Microstrip suitable technology to implement combiners at this level. Baseline amplifiers: 120W-250W (up to 350W) and 500W (based on IIFC, GM and Nautel) 120W amplifiers: 5-way 500W and 4-way 2000W 250W amplifiers: 8-way 2000W or 16-way 4000W 500W amplifiers: 4-way 2000W

650MHz Microstrip Straight forward up to few hundred Watts 30mils RT 6035HTC and 1oz copper: 120W and 100mils trace: total loss is dB/in, conductor losses dB/in, temperature rise ~4.3°C 500W and 250mils: total loss dB/in, temperature rise ~6.7°C

650MHz Microstrip 60mils RT 6035HTC and 1oz copper: 2000W and 250mils trace: total loss is dB/in, conductor losses dB/in, temperature rise ~20°C 4000W and 800mils: total loss dB/in, temperature rise ~20°C

650MHz Coax 7/16” HELIAX : –Attenuation ~3dB/100ft (0.0025dB/in) –Average power up to 2kW 1 5/8” HELIAX LDF7-50A: –Attenuation of ~0.58dB/100ft ( dB/in) –Average power ~5.8kW –Minimum bend radius: 8”

650MHz Combining up to 30kW 2.5kW 12-way combiner (or 2kW 16-way) –From 2.5kW modules coax connector (7/16”) blindmate to 12-way combiner –Input to combiner can use microstrip with a water cooled PCB, high thermal conductivity and low loss laminates. PCB along 12 (or 16) modules. –12-way radial combiner with balancing resistors on coldplates.

650MHz Combining up to 30kW Waveguide hybrid: –Conductor losses = dB/wavelength –Cross-section WR1150: 11.5”x5.75” (0.292m x 0.146m)