2018-02-14
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I. First Reading of the text “Energy from Inertial Fusion”.
1. Read paragraphs 1-2 quickly and try to understand what they are about and what information in the field of fusion is new to you.
2. Write down the technical terms, known to you in Russian.
3. Find in the paragraphs sentences about the concepts and methods described in the text.
II. Scanning Reading
1. Read the texts “Components”, “Solid-State Lasers”, “Light-Ion Accelerators”, “Heavy-Ion Acceletrators”.
2. Find:
a) in the text “Components” sentence explaining the term “the fusion cycle gain”
b) in the text “Solid-State Lasers” the sentence on the advantage of Nd: lasers.
c) in the text “Krypton Fluoride Gas Lasers” the sentence explaining why the use of Krypton fluoride gas lasers is complicated.
d) in the text “Light-Ion Accelerators” the sentence that explains the principle of operation of the accelerators above.
e) in the text “Heavy-Ion Accelerators” the sentence on different approaches to heavy-ion drivers.
3. Find in the text “Heavy-Ion Accelerators” the sentences on the acceleration of multiple beams.
4. Pick out the technical terms from the texts the ones аyou do not know. Refer to a dictionary if necessary.
III. Vocabulary and Word Study
A Vocabulary
1. driver n запускающее устройство, возбудитель
2. fusion n синтез
3. promise n перспектива
4. challenge n сложная проблема, задача
5. Nd glass laser лазер на стекле с неодимом
6. to envision v представлять себе
7. to imply v значить, подразумевать, предполагать
8. pulse rate частота повторения импульсов
9. yield of taget эффективность мишени
10.fusion cycle gain коэффициент усиления по циклу
11.cascade n зд. просыпание
12.inertial confinement инерционное удержание (плазмы)
13.power plant энергоустановка
14.driver power мощность запускающего устройства
15.irradience n облучённость, поверхностная плотность потока излучения
16.diode pump laser лазер с накачкой светодиодами
17.flashlamp pumped laser лазер с накачкой лампой-вспышкой
18.solid-state laser твердотельный лазер
19.confinement n удержание, ограничение
20.laser diode лазерный диод
21.to lase v подвергать воздействию лазера
22.peak adj максимальный
23.plausibly adv правдоподобно
24.debris n осколки, отходы
25. interface n устройство сопряжения
26. coupling n связь, взаимодействие
27. seed pulse импульс кристалла-затравки
28. pulse technique импульсный метод
pulse power действующее значение мощности импульса
29. ignition n зажигание
30.burn прожигание, отжиг
31. wattage n потребляемая мощность
32. diode array диодная матрица
33. wall plug штепсельная розетка
34. excimer laser эксимерный лазер
35.gap n разрыв, цель; искровой промежуток; запрещённая энергетическая зона
36. breeding размножение
37. blanket n зона воспроизводства
38. breeder n реактор-размножитель
39. grazing incidence скользящее падение
40. dump опрокидыватель
41. fluency n гладкость, плавность
42. angle of repose угол естественного откоса
43. waist n сужение
44. drop tower колонна понижения
45.interlock n внутреннее крепление
46. redundancy n избыточность
47. tendon n предварительно напряжённая арматура
48. to conceive полагать, замышлять;
49. fission n деление
50. space charge implosion пространственный заряд; взрыв, направленный внутрь
Notes to the text
inertial confinement fusion – ядерный синтез с инерционным удержанием плазмы
ceramic granule cascade - просыпание керамических гранул
a self-renewing liquid first wall – самовозобновляющаяся первая стена из жидкости
gravity fed solid Li2 O ceramic granules – твёрдые керамические гранулы из
Li2 O, подаваемые под воздействием силы тяжести
low-activation silicon carbide tiles –теплозащитные плитки из карбида кремния с низкой активацией
high-gain fusion target implosion – имплозия мишени при синтезе с высоким коэффициентом усиления
light-ion-fusion power plant designs – проекты силовой установки для синтеза лёгкими ионами
space-charge force - сила пространственного заряда
fusion cycle gain - коэффициент усиления по циклу расплава
net energy - энергия, которой можно пользоваться
В Word Study
1. Find the related verbs in the texts “Components”, “Solid-State Lasers”, “Krypton Fluoride Gas Lasers”, “Light-Ion Accelerators”, “Heavy Ion Accelerators”.
delivery performance production
reduction requirement operation
compression emission achievement
storage demonstration extraction
2. Find the related nouns in the texts abovementioned.
to reduce to induce to drive
to react to limit to fuse
to confine to react to perform
to emit to generate to propagate
3. Find the related adjectives
proportion magnet nucleus
linearization inertia gas
policy satisfaction nation
ENERGY FROM INERTIAL FUSION
Abridged
Progress in drivers, reactors and targets has made smaller, more flexible power plants feasible and has reduced the potential costs of developing them.
William J. Hogan, Roger Dangeiter and Gerald L. Kulcinski
1 Fusion is potentially a safe, clean energy source not limited by political boundaries. Magnetic and inertial fusion share this promise, but there are differences between them. An inertial fusion power plant is based on different physics and technology from a magnetic fusion power plant and therefore presents somewhat different benefits and challenges. The facilities required to demonstrate inertial fusion power are potentially much smaller. In this article we describe concepts for such a power plant, its beneficial features and a low-cost reactor test facility for developing practical fusion power.
2 Some of the challenges facing inertial confinement fusion as opposed to magnetic fusion include inertial confinement's different ignition and burn method, its pulsed nature, the high rate at which targets must be manufactured and put in place, and the technically difficult driver-reactor interface. Inertial fusion power plants must be designed to handle these technical problems in a satisfactory manner.
| The Cascade reactor. A flowing bed of ceramic granules, held against the wall by the rotating chamber, transforms thermonuclear energy into heat, breeds tritium and protects the structure from the effects of the thermonuclear microexplosions. The granules are fed into the ends of the reactor and slide along the wall to the waist, where they exit and are thrown into heat exchangers through tubes (not shown). The reactor wall consists of silicon carbide tiles held in compression with composite tendons. |
| Figure 1 |
3 Figure 1 shows one design concept, known as Cascade. Here ceramic granules cascade along the walls of the reaction chamber to collect the fusion energy, breed tritium and protect the structure from the short bursts of fusion energy.
Components
4 An inertial fusion power plant has four major components:
> The driver, a laser or particle accelerator that delivers energy to the fusion target
> The target factory, where targets are manufactured, filled with deuterium-tritium fuel and stored
>The reactor, where targets and driver beams are
brought together to produce thermonuclear microexplosions a few times a second
>The generator, which converts thermal energy to electricity.
5 Most drivers now envisioned can transport energy pulses large distances—for example, from a separate building. This separability implies that the driver can be maintained easily and can in principle support several reactors. The burning inertial fusion plasma is extremely small—much less than 1 mm in radius—and short lived— lasting from tens to hundreds of picoseconds.
6 Once the burning begins, performance can be affected only by events within a few centimeters, even if a particular effect travels at the speed of light. Thus one can design the reactor to contain the microexplosions and breed tritium without the designer having to worry about target performance. The reactor vacuum requirement is determined only by the requirements of beam propagation. One can vary the plant's power output by changing the pulse rate or yield of the target. In the development phase, targets with small gain and yield can be used in reduced-scale low-power reactor tests at reduced cost.
7 Central to the economics of any inertial fusion power plant is the fusion cycle gain.
The fusion cycle gain is the product of the driver efficiency η (the ratio of the energy delivered to the target and the energy supplied to the driver), the target gain G (the ratio of the thermonuclear yield and the driver energy), the nuclear energy multiplier M (the energy change due to neutron reactions) and the thermal-to-electric energy conversion efficiency e. In any inertial fusion power plant, the net electricity Pn is related to the gross electricity Pg through the power balance equation
Pn=Pg-Pa-Pd = Pg (l - fa - l/ηGMε)
Here Pa, which is equal to fa Pg, is the power used for auxiliary equipment, and Pd is the driver power. The driver's recirculating power fraction Pd /Pg is the inverse of the fusion cycle gain.
8 The cost of electricity is to a good approximation proportional to the yearly amortized capital cost divided by the net annual energy produced. To a first approximation, the capital cost of the reactor and conventional steam-cycle generator is proportional to Pt 0.6-0.8, where P t is the thermal power. Using this simple model, figure 2 shows the relative cost of electricity for a plant producing 1000 MW of electricity as a function of the fusion cycle gain and the total cost of the driver and target factory. A sharp knee defines the minimum acceptable fusion cycle gain, which is about 4 or 5. Further increases in fusion cycle gain do not lower the cost of electricity as rapidly as do driver and target factory cost reductions. Since the nuclear energy multiplier M is typically 1.05-1.15—due primarily to the exothermic reactions in lithium required to produce tritium—and the conversion efficiency ε is typically 0.35-0.45, the product ηG must be above about 10. This product determines the minimum gain necessary for any given driver. Since driver cost usually scales as some power (0.4-1.0) of driver energy, it is important to obtain this minimum gain at the lowest possible driver energy.
9 Note that to reach power break-even for the plant— that is, to produce enough power to operate the driver—requires a fusion cycle gain of only 1, if we ignore fa, which is usually only a few percent. That reduces the minimum required gain by a factor of 4 or 5. While reaching power break-even will not be an important technical requirement in itself, it is usually considered a noteworthy milestone on the way to economic competitiveness. The fact that break-even can be achieved at reduced gain therefore will help keep early inertial fusion reactor development costs low.
Solid-state lasers
10 The drive energy can be delivered by lasers or ion beams. The four concepts receiving significant effort in the US are solid-state lasers, KrF lasers, light-ion accelerators and heavy-ion accelerators.
11 Solid-state lasers, in particular Nd:glass lasers, have dominated inertial confinement fusion research to date. Almost all important target-physics experiments worldwide have been done with these drivers, for a simple reason: Beam irradiances of 10 14-1015 W/cm2 are required for fusion. At small drive energies the target mass can be reduced proportionately. However, the necessary beam intensity remains about the same, and lasers, even small ones, can provide the required values easily. Particle beams have much more difficulty providing high irradiance at low energy. Lasers enabled early low-cost target experiments to prove some of the fundamental features of inertial confinement fusion. In particular, Nd:glass lasers, because of their scalability, modularity, energy-storage capability, wavelength-conversion capability and advanced state of development, established their capabilities early on as an inertial confinement fusion research tool.
12 The most energetic and powerful laser in the world is Nova at Lawrence Livermore National Laboratory. Other large Nd:glass research lasers are the Gekko XII laser at Osaka University and the Omega laser at the University of Rochester. Numerous laboratories worldwide have smaller Nd:glass lasers.
13 Solid-state lasers were initially discounted for reactors because of the characteristics of flashlamp-pumped Nd:glass lasers—in particular, their inefficiency and low pulse rate.
14 Laser diodes with an efficiency of about 60% have been demonstrated. Such a diode's emission spectrum is quite narrow, and a second laser with an overlapping narrow absorption band can be designed, resulting in high overall laser efficiency. However, the diode's cost is proportional to the peak wattage required. Therefore, for a laser operating in a pulsed mode, the energy transfer time should be as long as possible. But this time is limited by the emission lifetime r of the crystalline laser. Thus the cost of the required diode array is proportional to the cost per peak watt of the array divided by the emission lifetime τ.
Krypton fluoride gas lasers
15 In excimer lasers using gases such as KrF, the gaseous lasing medium is pumped by an electric discharge or an electron beam. The lasing gas flows through heat exchangers to remove waste heat. The 250-nm wavelength and broad bandwidth of KrF lead to good coupling to the target.
16 The use of the KrF laser is made complicated by its very short spontaneous emission lifetime—that is, it does not store energy in the excited state for lengths of time longer than the desired extraction time. Thus for good efficiency light must be extracted during the entire pumping time. The anticipated pumping time, as dictated by pulsed-power requirements, is several hundred nanoseconds. Therefore the pulse must be shortened by a factor of 100.
| Figure 3 |
Recirculating heavy-ion driver with four beam lines accelerated progressively to 0.05 CeV in the low-energy ring, 1 GeV in the medium-energy ring and 10 GeV in the high-energy ring. The total energy put on the target is 4 MJ in a 10-nsec pulse. The direct cost is estimated to be under $500 million.
