# Presentation: 529311

## Technical Aspects of the Cryostat for a Front End Proton Driver Linac

*FNAL*
*26AUG04*
*Joel D. Fuerst*
*Physics Division*

## The Rare Isotope Accelerator (RIA)

## Cavities for the RIA Baseline Design

**9 different cavity types**
**6 dt structures @ 4.2 K**
**3 e-cells @ 2.1 K**
** ****Cavities 1,2,3,8,9 borrowed      from other accelerators**
**Cavities 4-7 under development**

## Baseline Linac cryomodules

**2****nd**** contains 9 ********.06****	****	****	****	****QTY 3**
**3****rd**** contains 8 ********.15****	****	****	****	****QTY 6**
**4****th**** contains 8 ********.26****	****	****	****	****QTY 10**
**5****th**** contains 7 ********.39****	****	****	****	****QTY 8**
**6****th**** contains 4 ********.49****	****	****	****	****QTY 14**
**7****th**** contains 4 ********.61****	****	****	****	****QTY 21**
**8****th**** contains 4 ********.81****	****	****	****	****QTY 8**
**RIB linac cryostats****	****	****	****	****QTY 9**
**Existing ATLAS cryostats****	****	****	****QTY 10**
***Cryostats for bunchers & magnets******	******	******QTY 61***

***Baseline Linac cryomodules***

## Cavities for the RIA ANL Update Design

**345 MHz ********=0.5**
**Triple-spoke**

**345 MHz ********=0.62**
**Triple-spoke**

**57.5 MHz QWR-based structures .02< ******** <0.14**

**115 MHz ********=0.15**
**Corrected QWR**

**172.5 MHz ********=0.14 HWR**

***Cavities for the RIA ANL Update Design***

## ATLAS Split Ring Cryomodule (1978)

** ****end loading**
** ****common vacuum space**
** ****forced flow LHe cooling**

## Positive Ion Injector (PII) Cryomodule (1990)

** ****space efficient design**
** ****top loading**
** ****common vacuums**
** ****stagnant bath LHe cooling**

## PII Cryomodule Online

## PII Cryomodule During Maintenance

**Space efficient**
**Top loading**
**Versatile**
**Straightforward alignment capability**

## Design Evolution

**Cylindrical**
**Common vacuum**
**Top loading**

## Design Evolution (cont’d)

**Cylindrical**
**Separate vacuums**
**End loading**

## Top-loading, Separated Vacuum Box Design

***Top-loading, Separated Vacuum Box Design***

## Cryomodule End Detail

**Top loading detail**
**Module-to-module**
**	****spacing**

## Module-to-Module Spacing

## RIA Cryomodule Cavity String

***RIA Cryomodule Cavity String***

**Clean-room assembly to this point**

**Cavities are sealed up in a clean environment**

**Separate beam and insulating vacuum systems**

## RIA Cryomodule Intermediate Assembly

***RIA Cryomodule Intermediate Assembly***

**Remove cavity assembly from clean room**

**Suspend clean assembly from top plate**

## RIA Cryomodule Final Assembly

***RIA Cryomodule Final Assembly***

**Lower assembly into vacuum vessel**

## Top-Loading Box Cryomodule with TSRs

## Magnetic Shield Assembly

**To minimize cost, the magnetic shield is assembled from 26 pieces of pre-annealed, flat sheet.  A simple, battened-seam design proved cost-effective to install and provides excellent shielding of the earth’s field, with the remnant field less than 20 mG over most of the interior volume.**

## Thermal Shield Assembly

**The thermal shield is made from sections of 1/16” ETP copper.  The sections hang from LN2 manifolds and stand off from the box with G10 buttons.**

## Cavity Assy Suspended from Cryomodule Lid

## Support Rod Geometry

**The support system is designed with the goal that there be no net shift in cavity elevation upon cooldown.  At the same time the structure should be adequately stiff to prevent swaying of the cold mass.  The support members are angled from the rails in towards the center of the module in such a way that the longitudinal shrinkage of the rails offsets the vertical shrinkage of the members and of the stainless steel cavity helium vessels.**

## Fabrication Completed in June 2004

**Constructed at Meyer Tool & Mfg:**
- Box
- Lid
- Thermal shield
- MLI blanket
- Magnetic shield
- Cryo & vac manifolds
- Support frame

## Prototype Fabrication (cont’d)

**O-ring sealed lid**
**Modular shield designs**
**He, N2, vac manifolds**
**Cold Al cavity support frame**

## Prototype Fabrication (cont’d)

**Modular shield designs**
**Mag shield assembled in sheets**
**Batten strips provide contact**

## Prototype Fabrication (cont’d)

## Assembly & test schedule

**JUN04****	****delivery of box cryomodule major components**
**AUG04****	****complete installation of thermal shield/MLI**
**SEP04****	****clean assembly of QWR & HWR on support frame**
**OCT04****	****complete dressed cavity/lid assembly, fit to box**
**OCT04****	****cool down for engineering run**
- Static heat leak
- Alignment
- Microphonics
- High-field operation
- Long-term testing

## Subsystems: Input Coupler & Slow Tuner

**Prototype coupler operational on double spoke cavity**
**revised coupler and pneumatic slow tuner to be tested on half-wave cavity**

## MB VTA Cavity Performance Data

## 4.2 K Residual Resistivity – 320-350 MHz Half-wave class structures

## Frequency Stability: Double Spoke

**Probability Density**

## Frequency Stability: ANL Half-wave

**Probability Density**

## Two-spoke Cavity Transfer Function

## Cavity Refrigeration Loads

**RIA operates CW, not pulsed**
**Dynamic >> static heat load**
**Aim for lowest R****res**** (high Q)**
**Design plant for turn-down**

## Baseline Driver Linac Design – Dynamic Loads

## ANL Update Linac Design – Dynamic Loads

**Include 2742 W static + 50 K shield + liquefaction + ****40% margin**
**Carnot power = 2622 kW**
**Installed power with ********Carnot**** of 30% + factor 1.3 = ****11.4 MW**
**Dissipation is 115-120W/m for TSR’s – microphonics issues**

**(Assumes Rres = 69 n******

## Comparison of Power Density

- Tevatron (warm iron)			~ 3.0 W/m
- RHIC (cold iron)				~ 1.8 W/m
**SRF:**
- SNS (pulsed)				~ 15 W/m
- CEBAF					~ 28 W/m
- RIA (cw)					~ 55 W/m,
- 			elements could exceed 100 W/m for triple spoke option

***Comparison of Power Density***

## Summary	

**Prototype box cryomodule to be tested Winter 04/05**
- $250K + cavities, couplers, tuners, instrumentation
- Separate beam and insulating vacuum
- SS, top loading, O-ring seal
- Suitable for all DT structures