# Presentation: 109304

## High Power RF Distribution and Control  in the HINS

**Alfred Moretti, **
**Oct 11 , 2007**

## Outline

- Description of Terms: Qo, Qext, QL,  β
- Description of 90 Deg Hybrid as a Vector Modulator.
- Description of the System
- Remarks
- Conclusions

## Definitions of Qo, Qext, QL,  β

**Qo = ****ω****E/P****L****, E=Stored Energy**
**                               ****P****L****= RF power Loss in **
**                                   ****walls of the cavity**
**                              **** ****ω****= 2****π****f, f is frequency**
**Q****ext****=****ω****E/P****rad, ****P****rad**** RF power radiated out**
**                ****the coupling hole and wave guide to**
**                 ****RF power source**
**Q****L****=****ωE****/(P****L**** +**** P****rad****);         ****β****= Qo/Q****ext****   **
**      ****Qo= Q****L****( 1+ ****β****);        ****τ****ε****= ****Q****L****/ ****π****f**
**                            **

**E**

**P****L**

**Empty Enclosed Cavity**

**E**

**P****L**

**P****rad**

## 90 Deg Hybrid as a Vector Modulator.

**Scattering Matrix**** S**
**                 ****0    0   C   jC**
**          ****S**** =     0    0   jC   C**
**                    ****C   jC  0     0**
**                    ****jC   C  0     0**
**                    **
**         ****b =  S   a     for a 3 dB Hybrid C=0.707 **** and**
**         ****b****2  ****=  Cos ((****θ****3**** – ****θ****4****)/2)   **
**Phase = (****θ****3**** ****+**** ****θ****4****)/****2**
**                          **

**a****1**

**a****2**

**a****3**

**a****4**

**b****4**

**b****1**

**b****3**

**b****2**

## Hybrid Output with 60 Degree Section Added to One of the Ferrite Phase Shifters

| 0 |
| --- |

**Amplitude vs Phase**

**Power output vs Phase.**

## Simplified Layout of the RF Fan-out for 8 GeV HINS Linac

_**This is simplified Layout of the high power RF distribution system**_
**      ****The 325 MHz high power line is as shown except it will have 3 main waveguide power Hybrid splitter and 4 smaller Hybrid splitters ****for Powering 6 directional coupler Arms as shown below for the cavities and the RFQ.                                                         **

**Directional Couplers**

**To Other**
**Hybrids**

**IQM’s**

**Circulators**

## High RF Power Distribution Meson Linac

**1.1 MW RFQ and RT Cavities**

**1.3 MW to SSR1 and SSR2 Cavities**

**0.547 MW to SSR1 Cavities**

**0.749 MW to SSR2 Cavities**

**Equal Power Split (EPS)**

**Equal Power Split**

**EPS**

**EPS**

**     ****RFQ   RT Cavities          SSR1              SSR1                       SSSR2**

**EPS**

**EPS**

**9 Cav**

**5Cav**

**4Cav**

## Directional Couplers Coupling Factors for each String of Cavities

**RT Cav at ****10**** ma**

**RT Cav at 16 ma**

**SSR1 Cavities No Current Difference**

**SSR2 Cavities No Current Difference**

**Note that the First 3 Cavities in the RT cavity string are the the 2 debunching Cavities and the first RT accelerating cavity used as a debuncher, **

## Coupling Factors to Minimize IQM Requirements Full Beam (18 MA) to No Beam HINS Driven by One Klystron

|  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Cavity |  | ToTal |  β | Qext | QoBeam |  β with | Ptransm | Δ Power |  |
|  | Qo | Pcu+Pbm | No Beam | No beam |  | Beam |  Γ  | Beam |  |
| RFQ |  |  |  |  |  |  |  | dB |  |
| 29.88 | 9000 | 524.75 | 1.5789474 | 5700 | 7717.9609 | 1.3540282 | 536.89341 | 0.5421824 |  |
| 16.6 | 9000 | 492 | 1.5789474 | 5700 | 8231.7073 | 1.4441592 | 508.80225 | -0.2333905 |  |
| 1.66 | 9000 | 454.2 | 1.5789474 | 5700 | 8916.7768 | 1.5643468 | 477.31779 | -0.5108045 |  |
| 18 | 8360 | 8.99 | 2.09 | 4000 | 5681.8242 | 1.4204561 | 9.2697133 | 1.2331441 | RT2 |
| 10mA | 8360 | 7.71 | 2.09 | 4000 | 6625.1102 | 1.6562776 | 8.2112292 | -0.5265813 |  |
| 1mA | 8360 | 6.27 | 2.09 | 4000 | 8146.6667 | 2.0366667 | 7.0971149 | -1.1598446 |  |
| 18 | 10051 | 13.102 | 2.51275 | 4000 | 7366.0282 | 1.8415071 | 14.361563 | 0.8575478 | RT3 |
| 10 | 10051 | 11.722 | 2.51275 | 4000 | 8233.2112 | 2.0583028 | 13.316602 | -0.3280827 |  |
| 1 | 10051 | 9.823 | 2.51275 | 4000 | 9824.8704 | 2.4562176 | 11.943166 | -0.8008223 |  |

## Beam Loading Effect and Feedback Compensation

**φ****s**

**Beam Induced Voltage**

**Beam Induced Cavity Voltage**

**φ****d**

**Required Acc. Voltage**

**Amplitude and Phase Feedback Control**

## Typical Chart of the Meson Linac Cavities

|  | RT Cavity #8 | SSR1 Cav#8 | SSR2 Cav#8 |
| --- | --- | --- | --- |
|         β | 2.624719 | 7104.275 | 5616.088 |
|        QL |   3,222.32 | 2.6741E5 |  4.4507E5 |
|        τε

Beam time |   0.991 us |  261.91 us

Need Apply Attenuation so it arrives same Beam time | 435.91 us

302.13 us |

**Beam Time = .6931 ****τ****ε**

## Reflected Power with and without beam

**Matched Point at beam time 26 ma**

**No Beam Case Pulse Shape**

**26 ma Case**

## Conclusions

**It maybe possible with one set of vector modulator per cavity to commission the HINS linac at low current upto 16 mA with one 2.5 MW, 325 MHz Klystron.**
**Major Components are out for bids and under study.**
**Variable (+/- 0.5 dB) Hybrids (Power dividers) Vendor solitications are in progress with promising results.**
**Need simulation of the Superconducting cavity section of the meson Linac to determine Feedback and Feed forward requirements. The only simulation we have was done by Marcus Huening 3 years ago. His numbers are at best case minmum +/- 8 Deg Phase and +/- 1 dB amplitude.**
**He consider micro-phonics, Lorentz force detuning, jitter**
**     ****in energy, phase and charge.**