physics

ITER Neutral Beam Test Facility

ITER Neutral Beam Test Facility is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand ITER Neutral Beam Test Facility rather than just read about it. In short: The ITER Neutral Beam Test Facility is a part of the International Thermonuclear Experimental Reactor (ITER) in Padova, Veneto, Italy. The facility will host the full-scale prototype of the reactor's neutral beam injector, MITICA (Megavolt ITer Injector & Concept Advancement), and a smaller prototype of its ion source, SPIDER (Source for the Production of Ions of Deuterium Extracted from a Radio frequency plasma).

Key takeaways

ITER Neutral Beam Test Facility belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect ITER Neutral Beam Test Facility to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of ITER Neutral Beam Test Facility from memory before moving on to harder problems.

Reference excerpt

The ITER Neutral Beam Test Facility is a part of the International Thermonuclear Experimental Reactor (ITER) in Padova, Veneto, Italy. The facility will host the full-scale prototype of the reactor's neutral beam injector, MITICA (Megavolt ITer Injector & Concept Advancement), and a smaller prototype of its ion source, SPIDER (Source for the Production of Ions of Deuterium Extracted from a Radio frequency plasma). SPIDER started its operation in June 2018. SPIDER will be used to optimize the ion beam source, to optimize the use of caesium vapor, and to verify the uniformity of the extracted ion beam also during long pulses.

ITER heating neutral beams To deliver power to the fusion plasma in ITER, two heating neutral beam injectors will be installed. They are designed to provide the power of 17 MW each, through the 23 m beamlines, up to the four-meter diameter container: in order to deposit sufficient heating power in the plasma core instead of the plasma edges, the beam particle energy shall be about 1 MeV, thus increasing the neutral beam system complexity to an unprecedented level. This will be the main auxiliary heating system of the reactor. Due to its low conversion efficiency, the neutral beam injector first needs to start a precursor negative ion beam of 40 A, and then neutralizes it by passing it through a gas cell (with an efficiency < 60%), and then by a residual ion dump (the remaining 40—20% negative, 20% positive). The neutralized beam is then dumped on a calorimeter during conditioning phases, or coupled with the plasma. Further reionization losses or interception with the mechanical components reduce its current to 17 A.

Purposes

The role of the test facility includes research and development on the following topics:

voltage holding: due to neutron environment, this will be the first beam source at -1 MV with vacuum insulation instead of gas insulation (SF6 gas is typically used); negative ion formation: the requirement on the extracted current density from the cesiated ion source is at the limit of the present technology of plasma ion sources. beam optics: the precursor ion beam is generated in a multigrid electrostatic accelerator, having 1280 apertures in each of the 7 grids composing it. Since the overall width of the beam along the beam drift (about 25 m) is due to the optics of each of the 1280 beamlets, the grid alignment and the disturbances produced by magnetic fields and electrostatic error fields are to be carefully verified. vacuum pumps: two 8 m long, 1.6 m high cryopumps will be installed on each side of the vacuum vessel. The fatigue life of components operating with cycles between 4 K and 400 K is to be verified. heat load on mechanical components: on the electrodes used for beam acceleration, and along the beam path, mechanical components are subject to very high thermal loads. These loads are continuously applied during long pulses, up to 1 h. These loads are anyhow lower than the heat loads expected on the ITER divertor plates.

Prototypes at the NBTF

SPIDER is the first large experimental devices to start the operation at the test facility (May 2018). The components of MITICA are currently under procurement, with its first operation expected in late 2023.

SPIDER The design parameters of SPIDER are the following:

Type: caesiated surface-plasma negative ion source Plasma source: 8 cylindrical RF drivers, operated at 1 MHz, connected to a single 0.8 m × 1.6 m × 0.25 m expansion chamber Process gas: hydrogen or deuterium Extracted hydrogen negative ion beam current: 54 A (target value) Electrodes and nominal voltages: Plasma Grid (-110 kV), Extraction Grid (-100 kV), Grounded Grid (0 V) Number of beamlets and multi-beamlet beam pattern: 1280 beamlets separated into 4 × 4 beamlet groups of 5 × 16 beamlets each During 2018, the plasma discharge by eight ion source RF drivers were optimised. In 2019 the operation with hydrogen negative ion beam begun: for the first year, SPIDER will operate with a reduced number of beamlets (80 instead of 1280) due to limitations in the vacuum system. In 2021, the first operation with caesium was performed.

Capabilities The capabilities of SPIDER and MITICA are listed in the following table in comparison with the objectives of the ITER Heating Neutral Beam and with other existing devices based on RF-driven sources. The obtained results reported in table refers to the operation at low filling pressure of 0.3 Pa; a marked improvement of performances is found for higher operating pressures, but a low pressure is required to minimise the heat loads due to stray particles, generated by interaction of the beam ions with the background gas along the multi-grid electrostatic accelerator of MITICA and ITER HNB sources.

Illustrations

Worked examples

Example 1 — a first encounter with ITER Neutral Beam Test Facility

Start with the simplest possible case. Write down what ITER Neutral Beam Test Facility claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to ITER Neutral Beam Test Facility before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about ITER Neutral Beam Test Facility ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of ITER Neutral Beam Test Facility

In research: ITER Neutral Beam Test Facility appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses ITER Neutral Beam Test Facility in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: ITER Neutral Beam Test Facility is common in secondary-school and first-year university syllabi. It links to neighbouring topics ITER, Particle physics facilities, Science and technology in Italy, so understanding it makes those chapters shorter.
In everyday life: Look for ITER Neutral Beam Test Facility outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “ITER Neutral Beam Test Facility” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study ITER Neutral Beam Test Facility in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what ITER Neutral Beam Test Facility means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain ITER Neutral Beam Test Facility out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is ITER Neutral Beam Test Facility in simple terms?

Why does ITER Neutral Beam Test Facility matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study ITER Neutral Beam Test Facility?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on ITER Neutral Beam Test Facility.