Status of RFCC-Module Development

Derun Li

Center for Beam Physics

Lawrence Berkeley National Laboratory

MICE Collaboration Meeting at INFN-LNF, Frascati, ITALY

June 26 ~ 29, 2005

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 2

The RFCC-Module in MICE

Coupling Coils

Eight 201 MHz cavities

Power couplers

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 3

Overview

Status and development Progress on the 201 MHz Prototype Cavity

(MUCOOL/MICE) Current level of completion RF couplers Curved Be windows Other accessories High power test at MTA, FNAL (development)

Coupling coil magnet (M. Green) Forces and quench protections

Integration to AFC module (W. Lau/S. Virostek)

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 4

Status of the cavity

In collaboration with J-Lab, U. of Mississippi, Oxford University Cavity fabrication: e-beam welding, EP and cleaning Power couplers: assembly and high power tests at SNS Vacuum assembly, …, shipping Curved Be windows

In MTA, FNAL Preparation for accepting the cavity Cleaning room purchased and will allow us for in situ assembly

of Couplers Window replacement Inspection of cavity

Low power measurement: frequency and coupling High power test at MTA, FNAL

Plan being developed

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 5

Cavity: Current Level of Completion

E-beam welding Ports Water cooling lines • Couplers assembled first time (mid-April-2005)• First low power measurement

• frequency ~ 199.5 MHz• coupling ~ 5 (max)• Q ~ 5000

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 6

Cavity Progress (Apr-2005)

Ready for mechanical cleaning and EPCouplers ready for conditioning

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 7

Cavity Progress: EP (June-05)

U-Shape Electrode

After 1st EP run (Early June 2005)

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 8

Cavity Status

• EP setup works, but the first EF was not satisfactory– ~ 13 lbs of copper removed– 40.6 in3 removed (0.32 lb/in3)– Cavity interior surface area: ~ 4700 in2

– Average thickness removed: 8.6 mils (219 microns)– Amounts to 3.4% to 5.0% of the initial thickness– Green crystals developed due to the saturated solution– Un-even surface and hard to clean away Mechanical cleaning again (over last weekend)

• 2nd EP under way– New solution– New chiller to cool the electrode– More cautiously

• Expect the cavity at MTA next month (July 2005)

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 9

Cavity Development in UK

• Recent development in UK (K. Long, Graham Gosling)– Cavity fabrication of the RFCC-module

• 1st meeting in June 15, 2005– Exchange ideas and information for

cavity fabrication and future development

– More meetings in the future (?)Tuner and mounting ideas

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 10

RF Power

Two couplers

Load Two Couplers (ready!)─ Critical coupling─ Ceramic windows are integrated

in the couplers─ Design and built at LBNL ─ Conditioning started using 805

MHz RF power at the SNS ─ Good vacuum ~ low 10-8 T─ Achieved 600 kW in TW mode

(matched load)─ Achieved 10 kW average power (~

9 kW average for nominal NF parameters)

─ Achieved 2.4 MW peak power in SW mode (at variable short positions)

─ Ceramic windows work fine during two weeks of the RF conditioning

RF Couplers

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 11

Curved Be Windows

• Succeeded in two curved Be windows so far for the 201-MHz cavity

• The windows are

0.38 mm thick, 420 mm diameter

• RF heating ~100 watts per window with ∆T~ 55 degrees for nominal Study-II parameters

• Window is formed by applying a die at elevated temperature

• Copper frame is brazed to Be window

• Be windows will be Ti-N coated shortly

• Asymmetry RF heating

420 mm

Curved-in window experiences 40% more RF heating than the one that curved-out- Small changes respect to overall RF power dissipation on the cavity - FEA (in collaboration with Oxford group) indicates the window should still work

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 12

Support Stand/Manual Tuner

•Manual tuner consists of thick aluminum plates connected by adjustable struts

•Tuner allows cavity frequency adjustment while providing support for interior vacuum load

•Parts for tuner fabricated in U. of Miss. Shop, and now at J-Lab

•Support stand attaches to one tuner plate and allows cavity to be placed adjacent to MTA magnet

Support design and construction have completed, now at J-Lab

MTA (Lab G) Magnet

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 13

The Cavity & its accessories

Need careful planning and coordination!

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 14

High Power Test at MTA

Plans under way– Coordination among LBNL, J-Lab, ANL and FNAL– Diagnostics (identified in last MICE meeting in Berkeley)– Preliminary plan so far

> In situ assembly of couplers, vacuum pump and gauges> Power splitter (Tee) at 6” coaxial transmission lines> Transitions to 4” coaxial lines with elbows to the couplers> Ti-N coated flat copper windows

> In situ baking (choices: hot N2 or water)

> Low power RF measurement of frequency and Q> Coupling balance and adjustment> Calibration of RF probes> Conditioning without magnetic field first

– Suggestions are very welcome

MICE Collaboration Mgt, Frascati, ItalyJune 26-29, 2005

Status of the RFCC-Module Derun Li

Center for Beam Physics LBNL Page 15

Summary

• Cavity fabrication is nearly complete with unexpected delays– EP + pressured water rinsing– Packing and shipping to MTA, FNAL

• Two couplers have been high power processed and ready for final assembly at MTA

• Significant progress on curved Be window• High power test plans being developed

• Recent development of RFCC-module in UK– MICE tuner ideas can be tested at RM and low power – Integration of RF coupler to MICE RFCC-module– Future cavity fabrication