1. 650 MHz Solid State RF Power development at RRCAT
Indian Institutions and Fermi lab Interaction Meeting
P. R. Hannurkar, Akhilesh Jain, M. R. Lad RF Systems Division RRCAT, Indore

2. RF Systems RD & D
RF Systems division, RRCAT is responsible for the design and development of RF systems for particle accelerators. It includes –
High power amplifiers based on tetrodes, klystrons, IOTs and transistors
Low level RF control and interlocks
High voltage DC power supplies and
Engineering design of coaxial and waveguide based RF components.
Systems for Indus-1 and Indus-2 synchrotron radiation sources have been successfully commissioned.
IOT based amplifier for Indus-2 upgrade is under progress.
Development of solid state amplifiers operating at MHz for Indus-2 is in progress.
Two units of 15 kW solid state amplifiers commissioned recently. Technology development to reach kW RF power level is in progress.
Work on 30 kW 650 MHz solid state amplifiers for powering SCRF cavities, has been initiated.

3. Solid State Amplifier Experience
RD & D in RRCAT
1 kW Solid State RF Amplifier for Booster Synchrotron
2 Nos SSPA at 15 kW, MHz operational in Indus-2 SRS
4 kW, 352 MHz SSPA as test stand
2kW (pulse), 352 MHz SSPA
650 MHz RF Amplifier module and associated RF components
Technology has been established for Power Divider, combiner, Amplifier modules, Directional couplers, LLRF, and RF dummy loads - all needed for making a complete system.

4. 1 kW Solid State RF Amplifier for Booster Synchrotron
Tetrode Tube based RF Amplifier has been replaced by 1 kW Solid State Amplifier for Booster Synchrotron. This has resulted in the improved performance.
Frequency
31.6 MHz
Output Power
1 kW
Mode of Operation CW
Gain
55 dB
Harmonics
-45 dBc
Efficiency
48 %
Gain characteristics of
1kW RF amplifiers
250 W RF Amplifier Module
1kW RF Amplifier

5. Indus-2 RF System Modular RF system at 505.8 MHz
1500 kV cavity gap voltage.
64 kW Multi beam Klystrons
RF Transmitters

6. 15 kW Amplifier
15 kW Amplifier commissioned in Indus-2 SRS
Two 15kW SSPA have been built and deployed in Indus-2 to energize RF cavities. With addition of these amplifiers, 100 mA at 2.3GeV was achieved.

7. 8 kW Solid State Amplifier Scheme for Indus-2
8kW unit is housed in a single euro rack with 32 amplifier modules of 320W RF power
To cater immediate requirement in Indus-2 accelerator , development of 60kW solid state amplifier is under progress at MHz. As a part of this project, two units of 8kW RF amplifier have been developed and tested successfully.
8 kW Solid State Amplifier architecture
8 kW, MHz Solid State Amplifier

8. MHz 320W RF Amplifier
RF PA module, operating at 320 W, with 28V DC bias, is workhorse for 8 kW amplifiers. specifications are listed below.
Sr.
Parameter
Value 1
Rated RF Power Output
320 W 2
Operating frequency and 1 dB Bandwidth
505.8 MHz, ± 5 MHz 3
Power 1db Compression
300 W 4
Operating Mode/ Class of operation
CW/ AB 5
Power Gain
15 dB 6
Input and output Impedance
50  7
Power Added Efficiency
50 % 8
Harmonic Distortion
-30 dBc 9
Spurious Output
-35 dBc 10
Input VSWR
1.2 11
Cooling
Water Cooled
Additional Specifications for 8 kW Amplifier
Sr.
Parameter
Value 1
Controls
System Enable, System ON/OFF, RF ON/OFF, system Shutdown, Emergency Trip 2
Front Panel Meter
Forward & Reflected Powers, System & alarm status 3
Primary Power
V, 47-63Hz, 3 Phase 4
External Protection
Excessive Reflection, over temperature, overdrive

9. Indus-2 60 kW Design Scheme
Scheme for 60 kW solid state amplifier -
30 kW RF power will be obtained by summing output of four 8 kW units.
Two 30 kW will be combined to get 60 kW RF power.

10. InPAC - 2011, IUAC, New Delhi Feb 15-18, 2011
RF Power Combiners
Using radial topology, novel 8-way and 16-way combiners, operating at 352, and 704 MHz have been developed.
Successful experimental work encouraged to develop 15 and 20 kW 2-way structure.
2kW 8- way combiners at 352,
505.8 and 704 MHz
4kW 16- way
Unit at 352 MHz
15kW 2- way combiner at 650 MHz ->
Work published in Rev of Sci Instru, Jan 2009
InPAC , IUAC, New Delhi Feb 15-18, 2011

11. Rigid coaxial transmission line Power combiners
16-way 4kW Power
combiner
2-way 20 kW Power
combiner
All power combiners are made up of silver coated brass material. Output power is taken from 1-5/8”, 3-1/8” and 6-1/8” coaxial lines respectively in 4 kW, 20 kW and 40 kW combiners.
2-way 40 kW Power combiner

12. Wide-Band Directional Couplers
4 kW
1 kW
20 kW
Directional couplers are useful for measurement of forward and reflected RF power. Three types of directional couplers with different power handling capacity viz. 1 kW, 4 kW and 20 kW have been designed and tested. 1 kW coupler is very compact having length 70 mm. 4 kW coupler is 200mm and 20 kW is 320 mm long. All three items have been made of silver coated brass material.

13. 2kW Pulse Solid State Amplifiers
200W and 2kW pulse Solid State Amplifier Developed for H-
LINAC at 352MHz are shown here.
200W (peak) Amplifier at 352 MHz
Power (P1dB): 2kW Pulse
Power Gain: 60 dB
Pulse Width : 500 µsec
Pulse Repetition Freq. : 25 Hz
2kW (pulse) Solid State Amplifier at 352 MHz

14. 352 MHz Solid State Amplifiers
4kW level Solid State Amplifier at 352 and 8kW amplifier with High power 16-way radial power divider, combiner, 2-way combiner and directional coupler, developed in-house, are shown here.
4kW Solid State Amplifier at 352 MHz
Power Gain: dB
Pulse power: 5kW at 3% DF
8kW Solid State Amplifiers at 352 MHz
Power (P1dB): 8kW CW Power Gain: 63 dB
Measured Power transfer Performance of 4kW Amplifier at 352 MHz
Measured Gain, power and efficiency distribution of individual Amplifier modules used in 4kW Unit
Inset showing High power 16-way radial power divider, combiner, 2-way combiner and directional coupler

15. 650 MHz RF System
Requirement -for powering two cavities viz. LB-650 (beta=0.61) and HB-650 (beta=0.9) in the energy range of MeV.
Output power ~ kW for each type of cavity
Possible choice- IOT or Solid state based amplifier
For this power regime, Solid state RF amplifier seems better candidate as RF power source, due to many advantages.

16. 200 W module at 650 MHz
At 650 MHz, 200W module is developed.
Design studies and simulation have been carried out using Newer LDMOS device, operating at 50V to obtain 350 W. Its PCB layout design and prototyping is under progress.
200 W solid state amplifier with measured power

17. 650 MHz RF Components Developed at RRCAT
20W Low Power Driver
2-way 8 kW and 18kW Power combiners
Output : 3-1/8” EIA
200 W Amplifier Module
Gain: 13 dB
VSWR: 1.1
P1dB: 200W
Coaxial Transitions
3-1/8” EIA to 1-5/8” EIA
1-5/8” EIA to N Type
1 kW
4 kW
16-way 4kW Power combiner
Output : 1-5/8” EIA
20 kW
30kW, 80kW and 200kW RF Dummy Loads
DC to 800 MHz, VSWR: 1.1, Water cooled
Wide-Band Directional Couplers

18. Proposed Design Scheme1
N=16
8kW Unit scheme used in 30kW Amplifier 1 2 31 32
Driver
350W
modules +
RF Generator 16 17 4
30 kW
RF Generator
Driver
8 kW Units
30kW Amplifier Scheme + 2 3
8 kW
4 kW
Proposed scheme for 30kW solid state amplifier -
30kW power will be obtained by summing output of four 8kW units.
8kW unit will be housed in a single euro rack with 32 amplifier modules, each one using LDMOS giving output around 350 W.
Complete system consists of various blocks.

19. Thanks