Case Study:

Ion Source and Extraction
Power Supplies (ISEPS) for ITERTheInternational
Thermonuclear
Experimental Reactor (ITER) is aninternational research eﬀort aimed atdeveloping fusion as an abundant
energy source with low environmental
impact.
Thefacility
isunder
construction in Cadarache, France, andwill feature an experimental Tokamak
reactor. The EU, U.S., China, Japan,
South Korea, India and Russia are allparticipating, with the goal of testing
the integrated technologies, materials
and physics regimes necessary forcommercial production of fusion-basedenergy in the future.
To achieve fusion on Earth, the plasma
where the reaction takes place must beheated to about 150 million degrees
Celsius. One of the systems used toachieve these extreme temperatures is
the “neutral beam injector,” which
injects high-energy particles of thesame kind present in the reactor toproduce heating. ITER will make use of
two neutral beam injectors of 17 MW tocreate, accelerate and ﬁnally neutralize
the ions before they enter the plasma.
In the ﬁrst two stages of the neutralbeam injector, the ion source
generates a cloud of negative
Deuterium ions which are then3D rendering of ISEPS for SPIDER

extracted using the extraction grid.
OCEMPowerElectronics
wascommissioned by the organization
Fusion for Energy, which is overseeing
Europe’s contribution to ITER, toproduce the Ion Source and Extraction
Power Supplies (ISEPS) system topower these steps.
The ISEPS Project
The ISEPS project consists of four
separate systems: one prototype totest the SPIDER ion source; one
prototype installed as part of thefull-scale neutral beam injector test
system, called MITICA; and twosystems, ITER 1 and ITER 2, for each ofthe neutral beam injectors at thecompleted ITER facility. Each system iscomposed of high-voltage power
supplies, high-current power supplies,

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ISEPS - Ion Source and Extraction
Power Supplies for ITER

four radiofrequency (RF) generators, ahigh-performance
controlandmonitoring unit, and all the related
subsystems necessary to power andmanage the ion source and neutralbeam injector.
ISEPS has an overall power rating of 5
MVA and is made up of aheterogeneous set of components,
ranging from power distribution
equipment at 6.6 kV to high-voltage (upto 12 kV) and high-current (up to 5 kA)
solid-state power converters. Each RF
generator has a power capacity of 200
kW and an operating frequency of 1MHz, and is fed by a direct current
power supply of 12 kV with a 140A
output feed current.
The entire system is hosted inside an
air-insulated Faraday cage called theHVD (“high-voltage deck”) working at apotential to ground equal to the ions’accelerating voltage.
SPIDER: Source for the Production ofIons of Deuterium
The ﬁrst ISEPS systems is a prototype
for the “Source for the Production ofIons of Deuterium,” or SPIDER,
experiment, which is a 1:10 scaled

ISEPS main power supplies

prototype for the ITER 1 and 2 systems.
The prototype is being tested at thePadova Research on Injector Megavolt
Accelerator (PRIMA) facility in Italy,
which is dedicated to developing andtesting the ITER neutral beam injectors.
SPIDER’s accelerating voltage is about
100 kV DC compared to 1000 kV DC for
the other three ISEPS systems. Its
high-voltage deck sits on a raised
platform measuring 12 meters by 10meters, which for purposes of electricalisolation is insulated from the groundand away from any walls.
Factory acceptance tests for SPIDER
were successfully carried out at OCEM’s
headquarters over a three-weekperiod. First, test runs were conducted
for each of the major sub-assemblies ofISEPS, followed by power testing of thewhole system connected to one of theRFgenerators
suppliedbyasubcontractor. The power supplies andRF generators were tested at themaximum nominal power of 200 kW for
ISEPS overview

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ISEPS - Ion Source and Extraction
Power Supplies for ITER

a period of 15 minutes – a longer
duration than anticipated in the test
plan for such a high power level.
In April 2015, SPIDER was delivered tothe PRIMA facility in Padova andinstalled between June and September.
Commissioning, functional tests andsite tests took place in October andNovember, with site tests beginning inDecember.
SPIDER has allowed OCEM todemonstrate not just its technicalexpertise
but
also
its
projectmanagement and integration skills.
“OCEM Energy Technology have provento be highly skilled collaborators andhave shown great adaptability in termsof the demanding speciﬁcations forISEPS,” Fusion for Energy project teamleader Tullio Bonicelli said.
MITICA: Megavolt ITER Injector &Concept Advancement

Unique Characteristics of theISEPS Project
ITER’s neutral beam injectors haveseveral unique characteristics thatmake ISEPS an especially advanced
power system. Each pulse beam has
the following speciﬁcations:
Voltage — 1000 kV
Energy – 17 MW
Pulse length – 3600 seconds
While most neutral beams injectors
only require a pulse lasting a few
seconds, ITER’s will last for up to anhour at a time. The system’s overall
performance will be three orders ofmagnitude higher than existingneutral beam injectors.

OCEM has also begun designing thesecond ISEPS system, the one for the“Megavolt ITER Injector & Concept
Advancement,” or MITICA. MITICA will
include a second full-scale prototype of
the ISEPS systems that will be produced
for ITER’s two neutral beam injectors.
MITICA’s acceleration voltage will be 10times greater than SPIDER’s, or 1000
kV. While the SPIDER system's ISEPS isorganized on a single level, the MITICA
one will be a two-level system on araised high-voltage deck, with aninternal staircase. Like SPIDER, MITICA
will be installed in the PRIMA facility inPadova to study and test before theﬁnal neutral beam injector systems for
ITER are produced.

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MCF control electronics

Source Support Power Supplies cabinet

ISEPS - Ion Source and Extraction
Power Supplies for ITERSPIDER Components and Speciﬁcations
Extraction Grid power system (ISEG)• Capable of 12 kV at 140 A, voltage ripple < ± 1%
Four radiofrequency generator systems (ISRF)• Four generators 0.9 ÷ 1.1 MHz, each 200 kW on 50 Ω load (160 kW ± 30° loads)
Source Support Power Supplies power system (ISSS)• Plasma grid ﬁlter power supply, 0÷5000 A, 15 V
• Bias power supply, 600 A, 30 V
• Bias plate power supply,150 A, 30 V
• Two core snubber bias power supplies, 200 A, 50 V each
• Starter ﬁlament bias power supply, 4 A, 160 V• Six Caesium oven power supplies, 4 A, 160 V
Power distribution (ISPD)• Oil transformer rated 5MVA, 22/6.6kV insulated at 100 kV DC• Circuit breaker and distribution boards at 6.6 kV and 400 V• Resin cast transformers (200 kVA / 6.6 kV and 130 kVA / 400 V) to feed the 400 V loads grouped into two insulatedsubsystems
Local Control systems• “Slow control system” for conﬁguration, supervision and monitoring of the ISEPS• “Fast control system” for management of fast controls, feedback regulations and protection functions,interlocking of power system internal faults, and all high-speed communications

Scan the QR Code to watch
an interview withOCEM Power Electronics
Manager Giuseppe Taddia
on YouTube.

About Us
For more than 70 years, OCEM PowerElectronics has designed, manufactured
and installed power systems for premier
research laboratories around the world. Its
customized power systems are enablingadvances in the ﬁelds of plasma physics,
particle physics and medical research, anddriving advanced industries such astransportation and food processing.

OCEM Power Electronics
a division of Energy Technology Srl
Via della Solidarietà, 2/1
Località Crespellano
40056 Bologna - Italy+39 051 6656611
power@ocem.eu

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