Linac R&D UpdateMay 15, 2006

L-Band Source• Consists of a LLRF system (VME/Epics based), a SNS High

Voltage Converter Modulator (on loan), a Thales 2104C 5

MW klystron, a 5 MW isolator (from SPA Ferrite) and

pressurized (30 psig N2, no SF6) waveguide that feed two

experimental areas (one in the NLCTA enclosure that will

power an ILC prototype positron capture cavity, and one for a

coupler test stand).

• Source currently configured with a Thales 2104U klystron

and the waveguide terminated in a load just after the isolator.

– Expect to receive the TH2104C klystron on May 27.

Lead

Box

Con

tain

ing

Kly

stro

n

Pre

ssur

ized

WG

Load

Isol

ator

Current RF source layout with power terminated in a nearby load

L-Band Source (cont)• Have operated the system to produce 3.3 MW, 1 msec rf pulses at 5 Hz.

• System processed quickly although had several arc-monitor faults.

• Discovered arcing on some of the flange surfaces – found the flange

faces were not flat (5-10 mils) – also had properly tighten them.

– Have since learned much more about flanges from industry, DESY,

KEK and FNAL, not all of which is consistent

– For next test, have machined flat the flanges to 1 mil. Will try both

metal-to-metal and metal-metal gasket-metal transitions.

• Have since upgraded SNS modulator using parts provided by Bill Reass

at LANL. In process of testing it with water and resistor loads

SNS HVCM Modulator

Resistive Load and TH2104U Klystron

Waveguide Distribution

Coupler Test Stand

Capture Cavity

RF Switch

Positron Capture Cavity• Half cell parts complete for body

• Need to braze pairs, do a second machining and then

tune – expect to do in 6 weeks

• First windows available for test in 7 weeks

• Full cavity done in about 3 months (mid-August).

• Still low shop priority as LCLS submits rf work for gun.

• Recently completed installation drawings for NLCTA. Also

Boeing donation of solenoid approved – need to arrange

shipment to SLAC.

ILC Positron Capture Cavity Prototype

As Installed in NLCTA w/o Window

Coupler Development

• Have decided on basic

plan to test coupler

parts.

• Setup uses a

detachable center

conductor and 20 inch

long test sections

• Chris N and Gordon

working on rf and

mechanical design

Design of WG-to-Coax Adaptor

Multipacting Simulation of TTF3 Coupler

Bellows

Primaries -Green, Secondaries- RedPrimaries -Green, Secondaries- Red

“Cold Side”

SC Quad/BPM Status• Magnet received from DESY in January after initial testing there in a

vertical Dewar. Gas-filled leads received in March.

• With help of Tom Nicol at FNAL, developed a low heat loss, stable support

design for the He vessel. May adopt similar support structure for the ILC

linac.

• Cryostat currently being built in SLAC shops and magnet / quench system

being configured. Had discussion with Bldg 25 managers as to the logistics

to install He transfer lines (safety review planned). Consider

accelerometers to buy to vibrations tests.

• First tests of new magnet measuring coil planned during the next month

using a NC quad. SC quad measurements planned for August.

• BPM triplet built, installed on girder in ESA and operated during run that

started on April 24.

Cryostat and Cryogenic System

BPM Triplet Results from Recent Run(0.8 micron resolution, 1.4e10 electrons, Q of 500 for clean bunch separation)

http://ilcagenda.cern.ch/conferenceDisplay.py?confId=366