Kenneth Baptiste Group Members: S. Kwiatkowski (Group Leader) J. Julian, M. Vinco

1

The Lessons Learned Commissioning a New Klystron & Current Status of the ALS Storage

Ring RF System Upgrade

Kenneth Baptiste

Group Members: S. Kwiatkowski (Group Leader) J. Julian, M. Vinco

Lawrence Berkeley National Laboratory7th CWRF 2012 Workshop - BNL, May 7-11, 2012

So Far !

Outline

7th CWRF 2012 Workshop - BNL, May 7-11, 2012

• Scope, Schedule & Status of the SRRF Upgrade

• Lessons Learned• Waveguide Coupler Calibration, Klystron Flange, Adequate Test Load• Mod-Anode PS Ripple• Cathode HVPS Turn-On Transient

Electrostatic Shielding Filament PS Stability

• Mod-Anode Voltage Control during Cathode HVPS Fast Fault (Crowbar) Klystron Recovery - HV Conditioning

• First 2 Months of Operation

2

Phase I: a. Order 3 Thales 300kW klystron, install & operate 1, install 1 off-line, 1 spare

b. Run Philips 330kW klystron until Dec. 2012 c. 2nd 6 week installation shutdown (Jan. 3 – Feb. 14 2012)

d. Run 1st Thales klystron for 500mA User Op’s until 1st Qtr 2013e. Beginning in Spring 2012 disassemble Philips klystron &

assemble 2nd Thales klystron off-linePhase II: a. Order a new HVTR/PS to modify HVPS to 54kV@14A

b. ~8 week installation shutdown (1st Qtr 2013)c. Replace Crowbar/Filter cabinet with new HV Disconnect

Switch/Filter cabinetd. Replace 3-4 ILC’s with PLC control systeme. Run either Thales klystron for 500mA User Op’s until 1 Qtr

2014Phase III: a. Modify waveguide distribution (1 klystron per cavity, full power

klystron test, either klystron driving both cavities)b. Install new digital Low Level RF systemc. Install new RF Signal Diagnostic System

Upgrade Scope

7th CWRF 2012 Workshop - BNL, May 7-11, 2012 3

Magic Tee

CAV

#1

CAV

#2

ALS Storage Ring RF System

Kly. Cir.

Tuner Control

Klystron Efficiency

Loop

50W

Direct Fast Feedback Loop

Ampl. Mod.

Klystron Phase

Phase Detector

Cavity RF Amplitude Loop

Klystron Phase Loop

BEAM

Phase

Attn.

setpoint

setpoint

Slow Beam Phase

SRRF Master Phase

From MO

Control System

LabView App

Modulation Anode

100W

+

-

Tuner Control

Phase Detector

56 kV @ 12 A HVPS

Filter & Crowbar

330 kW

Existing SR RF System

∑


300 kW

80W

SRRF Upgrade, when Completed

Fil. PS Mod-A

Fil. PS Mod-A

ALS Storage Ring RF System

BEAM

FREF 500MHz

Cont

rol

S yst

em54/50 kV @ 14.5/16 A

HVPS

Filter & Discon-Switch

System PLC Controller: HVPS Intrlks, HVPS

Control, HPA Control

300 kW Klystron

CAV #2Cir.

CAV #1

Tuner Control

Cir.D

AC

ADC

ADC

ADC

BPF

PA DRIVER

BPF

BPF

BPF

/4 /8

ADC

2 WAY SPLITTER BP

F

/10

BPF

FPG

A

2 WAY SPLITTER

IF

IF

IF

500MHz

50 MHz

50 MHz

50 MHz

50 MHz

50 MHz

REF

CELL

FWD

REFL

LO 550 MHz

DA

CAD

CAD

CAD

C

BPF

PA DRIVER

BPF

BPF

BPF

/4 /8

ADC

2 WAY SPLITTER BP

F

/10

BPF

FPG

A IF

IF

IF

500MHz

50 MHz

50 MHz

50 MHz

50 MHz

50 MHz

REF

CELL

FWD

REFL

LO 550 MHz

Digital Board

Digital Board Analog Board

Analog Board

LLRF

Tuner Control

Type N Port

Blank

Type N Port

Blank

400kW 225kW

225kW

200kW

300 kW Klystron

Motorized W/G Switches (5)


RF Upgrade Layout


Klystron Site #2

Circulator

Cav 1 & HOM Filter

Cav 2 & HOM Filter

CirculatorLoad

Klystron Site #1

Circulator

CirculatorLoad

HV Dis-Con SW & Filter

Magic-T & Switches

Test Load

Operating Options:Kly #1 to Cav 1 (to 200kW)Kly #1 to both Cavs (300 kW)Kly #2 to Cav 2 (to 200kW)Kly #2 to both Cavs (300 kW)Either Kly to Testload (300 kW)

Shut

dow

n

Shut

dow

n

Shut

dow

n TB

D

7

Upgrade Schedule


Phase I

2010 2011 2012 2013 20141Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q

Install 1st Klystron

Test Kly’s1 & 2

Phase IIDesign, Build & Test HV Dis-Con Sw/Filter Cabinet

Modify HVPS

Replace Crowbar-

Filter w/HV Dis-Con Sw-

FilterOrder new HVTR/PS

Phase III

Design, Build & Test Low Level RF &

Controls

Shut

dow

n TB

D

Run new Kly #1

Order new Klystrons

Test Kly3

Modify Waveguide Install new

LLRF

Run on Existing Philips Klystron

Addition of Insertion Device(s)

Run on Two new Klystrons

7

Phase I - Status (Completed)


Klystron Site #2 Completed

Mod-Anode Cabinet

PLC

IP PS

Drv AmpFoc PS

8

Phase II - Status (in progress)


Klystron Site #1Filter, HV Dis-Con SW & MA Cabinets

9

Filter Cabinet

Phase II - Status (in progress)


HVTR/PS Replacement

Filter Cabinet

10

HV Dis-Con Switch Cabinet (24 modules)

IGBT Module

4kV, 40A

See Presentation this afternoon...High Voltage Power Supply for the ALS Storage Ring RF system-Disconnect Switch StatusSlawomir Kwiatkowski

Phase III – (in conversation)Low Level RF Plan


Why Digital?• No drift• Perfect calibration• Can be accurately

simulated/modeled• Can add remote control & diag• Extra features are cheap, don’t

compromise reliability

Why NOT Digital?• Adds >150 ns latency, can effect

closed loop dynamics• >-150dBc/Hz added noise, ADC

Flexible Platform• BPM• RF Phase & Amp Monitors• Feedback Systems

Signal Conditioning• Onboard – driven by

packaging• Offboard – modularity,

keep close to cavity

Larry Doolittle: EngineerLow Level RF Controls

Recent Experience• APEX VHF Gun RF

11

Commissioning New Klystron


Lessons Learned

WaveguideKlystron Output Flange


Klystron Output Flange• Spec’d flange type Wrong flange

deliveredSent drawings to manufacturer

Spacer

WaveguideCoupler Calibration & Test Load


FWD & REV Power Coupler• Spec’d coupling factors 0.4dB error

I didn’t check before installing

WR1800 Wedge Water

Load

Test Load• We have (2) 225kW Waveguide Water Wedge Loads

Circulator Reject and Magic-T Reject Placed short on Output Port 1 of Magic-T Placed 45° section and short on Output Port 2 of Magic-T

• The problems Could not increase the cooling flow high enough as we have reduced

flow for normal op’s (~40kW dissipated). VSWR effected as cooling flow increases. Could not get to saturated power.

WaveguideKly Flange, F/R Cplr, Test Load


Lessons Learned

• Waveguide – The problem with standards is that there are too many to choose from! CHECK, DOUBLE CHECK and the CHECK AGAIN!

• FWD/REV Power Coupler – CHECK, DOUBLE CHECK and the CHECK AGAIN!

• Test Load - If you want to check a new amplifier after delivery and installation make sure you have a rock-solid full power test load. 50Ω ,Stable Match, Adequately Cooled for Full CW power test.

You don’t want any worries about the load when you’re testing new amplifier.

Va = 30 kV, Vripple = 120Vpp !!

Mod-Anode HV PS Ripple


VfIC load

2

App Note 505• Switching Freq = 40kHz nFCnFC

VkHzmAC stnd 1.2 ,9.1 ,

274024

•Vk = -54kV, Ik = 9A•RFΦ = 9.25°/A Va, 2.5kV/A• Va, 270V/°

•Vk = -50kV, Ik = 7.3A•RFΦ = 8.25°/A Va, 2.7kV/A• Va, 330V/°

•Design Goal = <0.1°• Va-ripple < 27Vpp

Thales TH2161

L

1st Filter Design

CapCharger asDC HVPS40kV @ 12.5mA

VVnFkHz

mAV 7.2 , 16702

6

2st Filter Design,

Va = 30 kV, Vripple = 10Vpp

Power Supply

12.6nF 4.2nF

50kΩ

15MΩ

Va = 20 kV, Vripple = 120Vpp !!

Lessons Learned1. The regulator for the constant current source contributes low freq ripple (a few kHz). Not mentioned in Manufacturer Data Sheet or App Note.2. Va <22kV Not Good for User Beam Operations.3. Fortunate, since Va in range of 24kV – 35kV for User Beam Operations.4. Need a better filter for 70kHz.

Cathode HVPS Turn-On Transient


Turn-On Conditions• Klystron connected• HVTR/PS input = 2.5kVAC• HVTR/PS output = -48kV peak @ 25ms

-28kV after 250ms

17

Vk

Icap

IPSHVTR – 12 Pulse Rectifier – L/C Filter

Electrostatic Shielding


Fil PS

MA PS

PLC FOX

Mod-Anode Hot Deck• Open Frame Hot Deck for visibility & maint. Suseptable to E-Fields,

Installed shielding panels• Initially installed partially shielded cables Replaced with shielded

cables• Unshielded MA HVPS Enable Divider Replaced with

compensated divider

Electrostatic Interference


Filament PS – Configurable Linear PS• Output Over-Voltage Protection Disabled & replaced functionality w/PLC• Output Over-Current Protection Disabled & replaced functionality w/Fuse

& PLC• Current Mode Control Op-Amp Connected Op-Amp inputs to defined V

had unconnected inputs per to properly disable factory config instructions• Delayed Interference Remains Plan to switch to Current Mode Control

ATE 15-50M

Lessons Learned

• Transient due to HVPS Turn-On – Though I was aware of this transient, I didn’t fully appreciate its affect and thought the initial shielding of the electronics and commercial ps was good enough. If we could afford it, I would change the front-end of our HVPS to

have a soft-start.

• Electrostatic Interference/Shielding – I tried to save a few k$ by making a HV Divider and I routed cables away from high E-Field regions. In the end, this cost us over a week in commissioning time! If I could do this again I would schedule transient test time on

new electronics prior to connecting Klystron.

Electrostatic Shielding


Initial Issue: MA PS Enable Voltage Divider Interference• After ~20 hrs of RF testing with intermittent divider decided to disconnect &

rely on PLC only. Estimated turn off would be 2-3 PLC scan periods (~75ms)• Had a vacuum event in klystron which triggered a Crowbar of Cathode HVPS.• Had 2 more vacuum events in klystron at HV turn-on. MA interception?• Consulted with Thales Field Engineer who offered several solutions

Va = 10 kV, Cath HVPS Crowbar,MA PS Enable via PLC & HV Div,

w/Clamp Diode, < 1us delay

Mod-Anode Voltage ControlDuring Cathode HVPS Crowbar


MAPower Supply

12.6nF 4.2nF

15MΩ

FilamentPower Supply

CathodePower Supply

+

-

+

-

+-

50kΩ 20kΩ

Hot Deck

MA PS Enable Divider

PLC

F.OCables

Va = 10 kV, Cath HVPS CrowbarMA PS Enable via PLC & HV Div,

w/Clamp Diode, < 1us delay

Va = 10 kV, Cath HVPS Crowbar,MA PS Enable via HV Dic only

~1ms delay, plus ~800ms decay

Va = 10 kV, Cath. HVPS Crowbar,MA PS Enable via PLC only

~100ms delay, plus ~800ms decay

Va = 10 kV, HV Turn-On,MA PS Enable via PLC only

~80ms delay

Va = 10 kV, HV Turn-On,MA PS Enable via HV Div only

~1ms delay

Replaced

Intrlk

Klystron RecoveryHV Conditioning


Klystron Dis-connected from Cath HVPS, MA HVPS & Fil.• Hi-potted 3-4 hrs, checked vacuum No problems observed• Ran Filament PS Initial turn-on vacuum

current spike

Klystron Re-connected (MA tied to Cathode)• HV Conditioned, checked vacuum Significant outgassing

observed• HV Conditioned for ~60 hrs Several On/Off cycles to condition

Lessons Learned

• Va Control – Incorrectly “Thought” PLC was adequate and MA HVPS would pull down voltage when PS is disabled. It couldn’t, it had no means to accomplish this. Need to measure and “KNOW” before proceeding with “I

THINK...” no matter how much pressure you’re under. Try to listen to other people and understand what they are

saying. Its hard because you are so intent on solving “your” problem.

• HV Conditioning Have good vacuum monitoring of your Klystron as this enables

one to carefully re-condition. Have patience

Va Control during Vk Crowbar


Operation since Feb. 14, 2012


Hours on the Klystron• Black Heat 339 (half of nominal filament current)• Standby 2093 (nominal filament current)• HV 2022• Transmit 1823

Klystron Operating Parameters• Vk = -50.4kV Ik = 9.25A• Va = 31.8kV Ia = 3.3mA• Eff = 56.8% Gain = 40.3dB• μP = 1.60

Beam Losses• SRRF Faults 6 Crowbar Conduction issues

Magic-T Arc Fast Vacuum Valve RF Intrlk (MPS)

VVT Fan Spurious CrowbarHV SW Hi-potting -> Spurious Crowbar

Thank you


Acknowledgments:

Max Vinco

Slawomir Kwiatkowski

Jim Julian

Danny Holstein (Thales)

Documents

Kenneth Baptiste Group Members: S. Kwiatkowski (Group Leader) J. Julian, M. Vinco