# Presentation: 471500

## New Materials and Designs for High Power Fast  Phase ShiftersRobyn Madrak, Tech. Division

***New Materials and Designs for High Power Fast  Phase Shifters******Robyn Madrak, Tech. Division***

## FNAL HINS

-  ***90 MeV Linac under construction at Fermilab’s meson building ***
***(proves technical feasibility of an 8 GeV Linac*************,******  ******aka Proton Driver)***
*** ******The use of fast ferrite phase shifters will allow all cavities (and RFQ) to be driven by a single 2.5 MW, 325 MHz klystron => large cost savings***
*** ******(Use of shifters allows independent phase and amplitude control in each cavity)***
**********G.W. Foster and J. A. MacLachlan, Proceedings of Linac’02, Gyeong, Korea***

## HINS 325 MHz RF

## Vector (I/Q) Modulator:

***Phase Shifters***

***Vector (I/Q) Modulator:***

***Modulates phase and amplitude independently:***
****
**With ******** = (********2  *****- *********3****)/2**
****** ****= (********2  *****+ *********3****)/2**
***Output power ~ *****cos****2****(*********)***
***Phase shift ~ *******

***Four Port ***
***Branch Line Coupler***

**Input ****→**

**Output ****←**

- 1

- 2

- 3

- 4

******2**

******3**

## How it Works, and History

***How it Works, and History***

**In a coaxial line filled with some dielectric (******
**v = c/****√******
**We vary ******** and thus v and phase by varying **
**the magnetic field applied to the ferrite.**
***1961 Bell Labs: Boxer, Hershenov, & Landry***
*** ******7/8 in. coaxial line***
*** ******fully filled with Mg-Mn ferrite aluminate***
*** ******operated above ferrite gyromagnetic resonance for low losses***
*** ******perpendicularly biased***
*** ******1350 MHz w/10% bandwidth***
*** ******1us pulse length @ 500 pps***
*** ******300 kW single pass***
*** ******0.2 dB loss in 18 in. length***
*** ******24 in. of ferrite gives phase shift of 360****** ̊***

## Bell Labs Phase Shifter

***Bell Labs Phase Shifter***

- quarter wave matching
- section for 50

## Operates in full reflection mode

Use solenoid along with shifters: phase of reflected wave determined by  of ferrite ( depends upon applied H Field)

Ferrite is Al doped Yttrium Iron Garnet (YIG) – TCI Ceramics AL-400
     (lower loss than original Bell Labs material)

Coaxial geometry; propagation mode is quasi-TEM

large bandwidth compared to waveguide versions; can be used at 325 and 1300 MHz

Required phase shift range:  ±45o

Required rate: 1o/s

Power Rating: ~50kW or ~400kW

***Operates in full reflection mode***
***Use solenoid along with shifters: phase of reflected wave determined by ************ of ferrite (************ depends upon applied H Field)***
***Ferrite is Al doped Yttrium Iron Garnet (YIG)*** – ***TCI Ceramics AL-400***
***     ******(lower loss than original Bell Labs material)***
***Coaxial geometry; propagation mode is quasi-TEM***
***large bandwidth compared to waveguide versions; can be used at 325 and 1300 MHz***
***Required phase shift range: ****** ±45o***
***Required rate: 1******o/************s***
***Power Rating: ~50kW or ~400kW***

***Fermilab’s Ferrite Phase Shifter***

## 3 OD X 0.5 ID X 2.5 long garnet cylinder
Coax geometry is 50 Ω

***Coax geometry is 50 ******Ω***

***Designs Pursued***

***3************ OD X 1.1************ ID X 5************ long***
**Not *****50******Ω****** => use quarter wave matching section***

**Type I**

**Type II**

**Type III**

## 1.5 OD X 0.65 ID X 5 long garnet cylinder
Not 50 Ω => use quarter wave matching section

**Not *****50 ******Ω****** => use quarter wave matching section***

***Designs Pursued (Cont’d)***

***Center conductor is a shrink fit for insertion***
-  ***Types I and II****** are of larger diameter => higher power; will be used for ******RFQ****** (requires ~>400 kW)***
***Type III****** is smaller diameter/power => use for the rest of the ******cavities****** (< 50kW)***

## S11 (reflection meas.) for 15⁄8′′ OD shifter

- bias = 160 A

- bias = 460 A

- bias = 800 A

- Amplitude (dB)

- phase

**gyromagnetic **
**resonance;**
**lossy**

*f (resonance) =*
*2.8 MHz/oersted * H*

## S11 for 15⁄8′′  and 3 ′′ shifters

- red = 1 ***5⁄8 ′′***

- purple = 3*** ******′′***

- With 10dB attenuator in 3* **′′ shifter *
*(to separate traces)*

***larger OD shifter has more higher order modes;***
***OK for low frequency***
***Problem for 1.3 GHz***

***HOM’s are TE******nm******:***
***First HOM has***
********* ******=************(D+d)******√************/2***

## Fast Response Tests:
Have been done at FNAL with an in-house built fast power supply for the applied H field
For Type I & III

High Power Tests @ ANL APS: 352 MHz
APS klystron is 1.1 MW CW => Horan et. al reconfigured to  operate in pulsed mode: 4 ms pulses @ 1Hz, up to 500 kW
All three types have been tested to the point of failure
Since shifters operate in full reflection mode, coax must tolerate twice the peak voltage
In addition, Type III with branch line coupler

High Power @ 1300 MHz FNAL A0 photoinjector
Type II (earlier version*), up to 600 kW

* Five one inch cores stacked

***Have been done at FNAL with an in-house built fast power supply for the applied H field***
***For Type I & III***
***High Power Tests @ ANL APS: 352 MHz***
***APS klystron is 1.1 MW CW => ***_***Horan et. al***_*** reconfigured to  operate in pulsed mode: 4 ms pulses @ 1Hz, up to 500 kW***
***All three types have been tested to the point of failure***
***Since shifters operate in full reflection mode, coax must tolerate twice the peak voltage***
***In addition, Type III with branch line coupler***
***High Power @ 1300 MHz FNAL A0 photoinjector***
***Type II (earlier version*************), up to 600 kW***
********** Five one inch cores stacked***

***Measurements and Tests***

## Fast Response Measurements: 15⁄8′′ OD

*** ***
*** ******Useful phase shift range above resonance: ~50************s, 110****** ̊***
*** ******This gives an average slew rate of 2.2 ̊/************s ***
***(twice as fast as design spec)***

**solenoid**
**(#12 AWG wire)**

**slot**

**Ch 1:  Solenoid**
**Current (50A/div)**
**      **

**Ch 3: PhaseShift**
**(~17o /div)**

**gyromagnetic**
**resonance**

**useful phase shift range; low loss**

***Fast Response Measurements: 1******5⁄8′′ OD***

## Fast Response Measurements: 3′′ OD, 2.5′′ length

*** ******Useful phase shift range above resonance: ~250************s, 73****** ̊***
*** ******This gives an average slew rate of 0.3 ̊/************s ***
*** ******These results are using 2.5′′ of ferrite; in final design hope to use 5′′***
*** ******Response time is limited by power supply/solenoid inductance; will go faster with Copley power supply***

***Fast Response Measurements: 3******′′ OD, 2.5′′ length***

**solenoid**
**(#12 AWG wire)**

**3****1⁄8’’ coaxial line**

## Fast Response Measurements: 3′′ OD, 2.5′′ length

**From Copley**

## 352 MHz Power Tests at APS

***352 MHz Power Tests at APS***

***Type I shifter on test station:***

**phase shifter**

-  ***Type I shifter: 50Ω, 3” OD, 2.5” length(for RFQ)***
*** ******Large solenoid, Cu tubing, for water cooling***

## Measure phase shifts at three bias fields, gradually increasing power from 10 kW

Type I  (3’’ OD, 2.5’’ length): Shifter functioned well to 420 kW

Type II (3’’ OD, 5’’ length): functioned well to 275 kW, then began to arc at small hairline cracks 

Type III (1.5’’ OD, 5’’ length) : functioned well to 100 kW, at which point arcing occurred in quarter wave matching line

**Measure phase shifts at three bias fields, gradually increasing power from 10 kW**
***Type I  (3’’ OD, 2.5’’ length):****** Shifter functioned well to 420 kW***
***Type II (3’’ OD, 5’’ length):****** functioned well to 275 kW, then began to arc at small hairline cracks ***
***Type III (1.5’’ OD, 5’’ length) :****** functioned well to 100 kW, at which point arcing occurred in quarter wave matching line***

- for RFQ

- for cavities

## Type III: Phase Shift in High and Low Power Tests

***Type III: Phase Shift in High and Low Power Tests***

- 352 MHz:
- Power tests at ANL
- 325 MHz:
- Operation frequency

## Type I: Phase Shift in High and Low Power Tests

## Type II: Phase Shift in High and Low Power Tests

***Type II: Phase Shift in High and Low Power Tests***

## High Power Test with Phase Shifter and Hybrid

**Branch**
**line**
**coupler**

**short**

**phase**
**shifter**

**solenoid**

***High Power Test with Phase Shifter and Hybrid***

**directional coupler**

**directional coupler**

## High Power Test with Phase Shifter and Hybrid

_***Port 1***_***: input***
_***Port 2***_***: phase shifter***
_***Port 3***_***: short ***
***(in normal operation, a shifter)***
_***Port 4***_***: 50 ************ load***
***(normal operation – the cavity)***

*** ******With:***
******2***** ******= phase shift on port 2***
******3***** = phase shift on port 3***
***defining***
****** ****= (********2  *****- *********3****)/2**
***Output power ~ *****cos****2****(*********)***
***Phase shift ~ *******

***High Power Test with Phase Shifter and Hybrid***

## 1300 MHz Power Test

***1300 MHz Power Test***

-  ***Five 3******′′ OD cores, 0.5′′ long (2.5′′ total length)***
*** ******25 ************s wide pulses, 1Hz***
*** ******40****** ̊ phase shift up to 600kW***

## Conclusions/Summary

*** ******Three types of fast ferrite phase shifters have been built: two types of higher power rating (for RFQ), and one of a lower power rating (for other cavities)***
***These can tolerate the power levels for which they will be used***
***The speed of the response is suitable: twice as fast as the original spec.***
*** ******For more details, see proceedings of Linac’06 :                             ***
*** “******New Materials and Designs for High Power Fast  Phase Shifters”***