STUDY AND PROTOTYPING OF
POWER SUPPLIES AND KLYSTRON
MODULATORS
Carlos A. Martins
Instituto Superior Técnico (IST) – Technical University of Lisbon
Centre for Innovation in Electrical and Energy Engineering (CIEEE)
(formerly a section leader at CERN in the power converters group)
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
1
SUMMARY
1.- Introduction on Power Supplies for particle accelerators
- Classifications;
2.- Main issues to be considered in the design
- Load Regime (topology), Precision, EMC compliance, Remote controls, Safety,
Reliability/maintenability;
3.- Examples of magnet power supplies (CERN case study)
- “Of the shelf”;
- Custom made;
4.- Solid state klystron modulators for proton Linac´s
5.- Potential contributions from CIEEE / IST
6.- Conclusions
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
2
INTRODUCTION
POWER SUPPLIES FOR PARTICLE ACCELERATORS
Classification based on the load type
1.- Power Supplies for magnets
- beam bending magnets;
- beam correction magnets (steerers, quadrupoles, solenoids, sextupoles, etc.);
- beam kicking magnets (septa, kickers);
- “special purpose” (gamma transition, beam scope meters, etc.);
2.- Power Supplies for RF tubes
- Tetrodes for RF generators in particle sources;
- Klystron / IOT modulators for accelerating structures;
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
3
INTRODUCTION
POWER SUPPLIES FOR PARTICLE ACCELERATORS
Classification based on load regime
Regime mode
Energy
Cost /
efficiency Volume
Voltage (V), Current (I)
waveforms
1.- DC mode
Physics
Machine
V, I
• 1-quadrant (V+ ; I+);
Low
High
t(s)
DC Synchrotrons
Or
Superconducting
machines
0
2.- Function tracking
mode
• 1-quadrant (V+ ; I+);
• 2-quadrants (V+/- ; I+);
• 4-quadrants (V+/- ; I+/-)
V, I
Medium
Medium
t(s)
0
3.- Pulsed mode
• 2-quadrants (V+/- ; I+)
V, I
Highest
Lowest
t(ms)
0
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
Normal
conducting
Fast Cycling
Synchrotrons
Or Transfer Line
Bending
magnets
Normal
conducting
LINAC’s and
Transfer Lines
MAIN DESIGN CONSIDERATIONS
1. Load regime (power)
• selection of topology (DC, function tracking, pulsed);
• nº of quadrants;
• Cabling and AC feeders;
• Cooling (air natural or forced; water);
2. Precision
• Stability (over one year ?, one day ?, half an hour ?);
• Reproducibility (pulse to pulse);
• “Precision budget” should be established together with beam dynamics specialists;
• Impact mostly from the choice of DCCT’s (magnets supplies) or HV voltage
dividers (RF tube supplies);
• These complex sensor devices are manufactured by very few companies (i.e.
Danfysik, Hitec, North Star,...);
3. EMC compliance
• All power supplies should be compliant with international standards in terms of
EMC emissions and immunity. Specific testing campaigns shall be planned and
executed during prototyping and production acceptance;
• The guarantee that all systems (power supplies, instrumentation electronics, ...) will
perform correctly once integrated together in the machine
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
5
MAIN DESIGN CONSIDERATIONS – CONT.
4. Remote Control System
• Selection of the fieldbus (WorldFIP?, ScienceFIP?, Ethernet?, WhiteRabbit?, ...);
• Interface with the low-level controller part in the power supplies;
• Physical layout of the controller (single board?, cassette?, chassis?,...);
• Should be UNIQUE to all power supplies in the physics complex;
• Online monitoring, diagnosis and “post mortem” facilities;
5. Reliability and maintainability
• MTBF – Mean Time Between Failures (should be ~ 10 years, individually; if total
power supplies = 1000 -> Total MTBF = 4 days);
• Lifetime should be ~20 years by design (ageing of components like capacitors,
obsolescence, thermal cycling of semiconductors must be taken into
account);
• MTTR – Mean Time to Repair (should be ~1 hour);
• Spare parts and spare power supplies policy (shall be foreseen from the very
early stage of the project and included in call for tenders; inventory data-base
created and updated);
6. Safety
• Fire risks (special cables?);
• Access for operation (Grounding equipment, capacitor discharge systems,...);
• Presence of oil in HV equipments (leakage retainers, fire prevention systems, ...);
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
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EXAMPLES OF POWER SUPPLIES
(“OF THE SHELF”)
Danfysik
• Low voltage DC
Heinzinger
• Low voltage DC;
• High Voltage DC;
• Capacitor Chargers
FUG
Technix
Delta Elektronika
• High Voltage DC;
• Medium Voltage DC;
• Capacitor Chargers
• Low voltage DC
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
• High Voltage DC;
• Capacitor Chargers
Carlos Martins – IST / CIEEE
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EXAMPLES OF POWER SUPPLIES
(CUSTOM MADE - CERN CASE STUDY)
PS Gamma Transition
(500Apk, +/-6kVpk)
PS Pole Face Windings
(+/-250A, +/-1.2kV)
PS Pole Face Windings
(+/-1600A, +/-600V)
Function tracking type
Developed for
CERN PS Consolidation program
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
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EXAMPLES OF POWER SUPPLIES
(CUSTOM MADE - CERN CASE STUDY)
19”,3U
Electronics
crate 19”, 3U
Power crate
19”, 6U
500V
voltage
Septa
current
20A
300A
7 ms
current
1 ms
Linac2 &
PSB TL
Steerers
Linac2 &
Linac3
Quads
(Pulsed:
20Apk, 600Vpk,
5ms/5 Hz)
(Pulsed:
300Apk, 1kVpk,
1ms/5 Hz)
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
PS injection /
extraction Septa
(Pulsed:
20kApk, 300Vpk,
0.6ms/1 Hz)
Pulsed type
CERN Linac2, PS Booster & PS
Consolidation programs
Also foreseen for Linac4
Carlos Martins – IST / CIEEE
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SOLID STATE KLYSTRON MODULATORS
FOR PROTON LINAC’S
Typical Requirements
Klystron power supply
- Pulse width:
- Flat-top duration
- Precision at flat-top:
- HF ripple at flat-top:
- Repetition rate:
- Nominal voltage:
- Nominal current:
- Nominal power (peak):
- Rise/fall times (99% / 1%):
- Maximum energy in case of arc:
~2 ms
~1.5 ms
< 1%
< 0.1%
2..50 Hz
~120 kV
~20..100 A
~10 MW
~10% of Pulse width
< 20 J
Collector
(GND)
+
-
~ hundred kV
Shape of High Voltage Pulses
V
Rise time
Flat-top
Fall time
time
Cathode
(-)
Pulse width
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
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SOLID STATE KLYSTRON MODULATORS
FOR PROTON LINAC’S
•The FERMILAB / DESY type modulator
Simplified schematic, with
pulse transformer
120 kV, 140A, 2.3ms, 10 Hz
(Without pulse transformer)
Also foreseen for:
- Project X @ Fermilab;
- XFEL @ Desy;
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
11
SOLID STATE KLYSTRON MODULATORS
FOR PROTON LINAC’S
•CERN Prototype (3-MeV Test Stand & Linac4)
100 kV, 20A, 0.8ms, 2 Hz
Simplified schematics
Anode power Filament power
converter, PS3 converter, PS4
PS1, PS3, PS4 - Commercial
PS2 - CERN made
120 kV High voltage cables
DC
DC
120 kV High voltage connectors
Hign Frequency
ISOLATION
TRANSFORMER
DIODE
RECTIFIER
PULSE
TRANSFORMER
(OIL TANK)
12 kV max
DRIVER
DRIVER
Vout
VPS1 0.1
mF
K1
-120 kV
max
Capacitor bank charger
power converter, PS1
Main solid state
switches
K
F
KLYSTRON
(OIL TANK)
A
Capacitor
discharge
system
1:10
A - Anode;
C - Collector;
K - Cathode;
F - Filament
A1
VPS2
Droop compensation power
converter or “bouncer”, PS2
C
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
12
SOLID STATE KLYSTRON MODULATORS
FOR PROTON LINAC’S
• SLAC Prototype
Also a candidate for:
- ILC;
115 kV, 135A, 1.5 ms, 5 Hz
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
13
SOLID STATE KLYSTRON MODULATORS
FOR PROTON LINAC’S
• Oak Ridge (SNS) modulators
140 kV, 70A, 1.6ms, 60 Hz
(9.8 MWpk, 940 kWav)
AC/DC input
converter not
shown
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
14
SOLID STATE KLYSTRON MODULATORS
FOR PROTON LINAC’S
• J-PARC modulators
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
15
POTENTIAL CONTRIBUTIONS FROM
CIEEE / IST
On Power Supplies and Klystron Modulators:
1. Carry on Studies for the Technical Design Report and Work-Package Description
•
•
•
•
•
Define main parameters, types and quantities for each application (in close collaboration with
magnets team (magnet power supplies), RF team (klystron modulators) and beam dynamics team;
Propose topologies/references taking into account the market availability;
Define remote control system (in close collaboration with controls people);
Estimate costs, volumes, auxiliary requirements (water cooling, AC electrical feeders, AC and DC
cables);
Planning;
2. Studies on Klystron Modulator Topologies
•
•
•
Evaluate in detail the existing topologies;
Propose the most suited topology for ESS (High power, High repetition ratio);
Study in detail the adopted topology by simulation and small scale prototyping (~same voltage, ~10%
of rated power);
• Synergy with CERN possible;
Or alternatively (consulting):
• Participate in writing-up of technical specifications and test protocols;
• Evaluate commercial offers; follow-up of contracting milestones; participate in the testing campaign;
3. Realization of prototypes for “custom made” power supplies
4. Write-up technical specifications, test protocols. Follow-up of construction and
validation
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
16
CONCLUSIONS
1. Power Supplies and Klystron Modulators are key technologies in accelerators
•
•
“Klystron modulators are probably the second most challenging sub-systems in high duty-cycle
Linac’s, just after accelerating structures…” – Maurizio Vretenar, CERN Linac4 Project Leader;
Very few European and Worldwide companies are able to develop and produce such specific
equipment (particularly for klystron modulators)
2. “Of the Shelf” versus “customized” solutions should be carefully evaluated
•
•
•
At least 2 solid companies (preferably 3) shall be able to provide the same or equivalent “Of the shelf”
product (double source), to avoid risks of bankruptcy, monopoles in the long term future;
The project team shall have a “word to say” on the selection of the topology (technology); Do not
delegate entirely this responsibility to companies;
Careful about functional specifications (technical specifications would be preferable…): - Too
much freedom given to companies on “turn-key” solutions may put the whole project dependent on a
single company in terms of delays, performance, long term reliability and maintainability;
3. Close follow-up of companies’ technical activities is essential
•
•
•
•
•
•
Single contracts (not a long term based commercial exchange);
Companies main objective: Profit (which is perfectly fair and honourable);
Project main objectives: Systems ready on time according to specifications; Reliable and
maintainable in long term (20 years);
Be sure to get all documentation, knowledge and relevant information about the equipment;
Before placing a contract:- cross-check all parameters and technical details with the other partners of
the project;
Be sure the specifications are clear and cover all pertinent technical details. Companies will
challenge you on this capability…
Towards a Portuguese participation in the ESS project, 29th Jan. 2010, Lisbon
Carlos Martins – IST / CIEEE
17