Download presentation
Presentation is loading. Please wait.
1
Why are particle accelerators so inefficient?
Philippe Lebrun CERN, Geneva, Switzerland Workshop on Compact and Low-Consumption Magnet Design for Future Linear and Circular Colliders CERN, 9-12 October 2014
2
Workshop on Magnet Design Nov 2014
Why bother about efficiency? M. van der Hoeven, Energy efficiency report 2013, IEA Ph. Lebrun Workshop on Magnet Design Nov 2014
3
Workshop on Magnet Design Nov 2014
The largest energy resource M. van der Hoeven, Energy efficiency report 2013, IEA Ph. Lebrun Workshop on Magnet Design Nov 2014
4
Workshop on Magnet Design Nov 2014
Electricity price projections European Commission, Directorate-General for Energy EU energy trends to 2030, Reference Scenario 2010 CERN average Ph. Lebrun Workshop on Magnet Design Nov 2014
5
Accelerator βblack boxβ model
Electricity π· ππππ
Particle energy π¬ Accelerator/Collider Particles on target π΅ Luminosity π Heat πΈ Ph. Lebrun Workshop on Magnet Design Nov 2014
6
Accelerator βmulti black boxβ model
Infrastructure Accelerator systems βIntrinsicβ losses Electricity π· ππππ
Particle energy π¬ Beam power π· ππππ Stored energy πΎ ππππ Particles on target π΅ Luminosity π Heat Ph. Lebrun Workshop on Magnet Design Nov 2014
7
Workshop on Magnet Design Nov 2014
A two-step approach Understand relations between Performance parameters Particle energy πΈ Luminosity β Beam parameters Beam power π ππππ Beam stored energy π ππππ Analyse sources of losses βIntrinsicβ losses Synchrotron radiation Beam image currents Electron cloud Accelerator systems RF Magnets Vacuum Beam instrumentation β¦ Infrastructure Electrical distribution Cooling & ventilation Cryogenics Ph. Lebrun Workshop on Magnet Design Nov 2014
8
A two-step approach [1/2]
Understand relations between Performance parameters Particle energy πΈ Luminosity β Beam parameters Beam power π ππππ Beam stored energy π ππππ Analyse sources of losses βIntrinsicβ losses Synchrotron radiation Beam image currents Electron cloud Accelerator systems RF Magnets Vacuum Beam instrumentation β¦ Infrastructure Electrical distribution Cooling & ventilation Cryogenics Ph. Lebrun Workshop on Magnet Design Nov 2014
9
Beam power, particle energy, intensity Linear accelerators
Average beam power π ππππ =πΏπΌ πΈ π = π πππ π ππ’ππ π πΈ Example: ESS proton linac πΈ=2 GeV πΌ=62.5 mA πΏ=4 % π ππππ =5 MW average Beam current Particle energy Duty factor Repetition frequency Particles per pulse Ph. Lebrun Workshop on Magnet Design Nov 2014
10
Beam power, particle energy, luminosity Linear colliders
Lower-energy regime (small beamstrahlung) β ~ π½ π¦ π π¦ π ππππ πΈ High-energy regime (large beamstrahlung) β ~ π π§ π π¦ π ππππ πΈ Example: CLIC Beam power Particle energy Vertical beta at collision Vertical emittance Bunch length Ph. Lebrun Workshop on Magnet Design Nov 2014
11
Beam power, particle energy, intensity Circular accelerators
Beam energy π ππππ = π ππ’ππ π πΈ Average beam power π ππππ = π ππ’ππ π πΈ π ππ¦πππ Example: SPS (design) πΈ=400 GeV π ππ’ππ π =1013 π ππ¦πππ =5.8 s π ππππ =640 kJ π ππππ =110 kW Particles per pulse Particle energy [eV] Accelerator cycle period Ph. Lebrun Workshop on Magnet Design Nov 2014
12
Stored energy, particle energy, luminosity Circular colliders [1/2]
For round beams with crossing angle β= π π 2 π π π πππ£ πΎ 4π π π π½ β πΉ Noting that π ππππ = π 0 π 2 πΎ π π π π =πΈ π π π π Then β= 1 4π π 0 π 2 π πππ£ π π π π πΉ π½ β π ππππ = πΎ 4π π πππ£ π π π π πΉ π½ β π ππππ πΈ Number of bunches Particles per bunch Revolution frequency Geometrical factor Normalized emittance Beta function at collision Circumference Collision optics Injector chain Ph. Lebrun Workshop on Magnet Design Nov 2014
13
Avg. beam power, particle energy, luminosity Circular colliders [2/2]
Introducing βaverageβ beam power, i.e. beam stored energy divided by beam lifetime π ππ£π ππππ = π ππππ π ππππ ~ πΈβ π ππππ Example: LHC nominal πΈ=7 TeV πΌ=0.58 A β=1.0E34 cmβ2.sβ1 π ππππ =362 MJ taking π ππππ β10 h, then π ππ£π ππππ β10 kW i.e. about 20 kW for two beams Ph. Lebrun Workshop on Magnet Design Nov 2014
14
Workshop on Magnet Design Nov 2014
Collider COP For all types of colliders , the average beam power is proportional to the product of particle energy and luminosity We can then define a βcollider coefficient of performanceβ (CoCOP) as the product of collision energy and luminosity πΆππΆππ=2 πΈ β [E34 TeV.cmβ2.sβ1] The CoCOP can then be compared to the beam power for different machines, and the ratio πΆππΆππ/ π ππππ [E34 TeV.cm-2.s-1/MW] used to quantify the relation between beam power and collider performance Notes The CoCOP has the dimension of an inverse cross-section The CoCOP may be seen as an attempt to quantify the βphysics reachβ of the collider. However, it gives the same weight to energy and luminosity, which are both important but not equivalent. A βphysics coefficient of performanceβ (PhyCOP) could be defined by a Cobb-Douglas function πβπ¦πΆππ=2 πΈ β π with π<1 Ph. Lebrun Workshop on Magnet Design Nov 2014
15
Workshop on Magnet Design Nov 2014
Collider COP Ph. Lebrun Workshop on Magnet Design Nov 2014
16
Collider COP/beam power Note logarithmic scale
Ph. Lebrun Workshop on Magnet Design Nov 2014
17
A two-step approach [2/2]
Understand relations between Performance parameters Particle energy πΈ Luminosity β Beam parameters Beam power π ππππ Beam stored energy π ππππ Analyse sources of losses βIntrinsicβ losses Synchrotron radiation Beam image currents Electron cloud Accelerator systems RF Magnets Vacuum Beam instrumentation β¦ Infrastructure Electrical distribution Cooling & ventilation Cryogenics Ph. Lebrun Workshop on Magnet Design Nov 2014
18
Example of analysis CLIC power consumption by technical system
500 GeV A Total 272 MW 1.5 TeV Total 364 MW 3 TeV Total 589 MW CV: cooling & ventilation, NW: electrical network losses, BIC: beam instrumentation & control Ph. Lebrun Workshop on Magnet Design Nov 2014
19
Collider power and efficiency
Ph. Lebrun Workshop on Magnet Design Nov 2014
20
Collider efficiencies Note logarithmic scale
Ph. Lebrun Workshop on Magnet Design Nov 2014
21
Sankey diagrams are useful tools CLIC power flow
Power flow for the main RF system of CLIC at 3 TeV Overall power flow for CLIC at 3 TeV Ph. Lebrun Workshop on Magnet Design Nov 2014
22
Accelerator systems: magnets Power consumption
Normal conducting (copper) Power dissipation per unit length π πΏ ~ π πΆπ’ ππ΅ Total power dissipation π ~ π πΆπ’ ππ΅π
~ π πΆπ’ π πΈ ππππ -> power dissipation can be reduced by choosing a low current density Superconducting Total power (refrigeration) π ~ πΏ ~ π
-> independent of magnetic field
23
Magnet systems for circular accelerators Specific power consumption
Superconductivity and higher fields break the canonical ~ 250 kW/GeV specific power consumption of conventional synchrotron magnets
24
Accelerator systems: RF Development of high-efficiency modulators
Useful flat-top Energy 22MW*140ΞΌs = 3.08kJ Rise/fall time energy 22MW*5ΞΌs*2/3= 0.07kJ Set-up time energy 22MW*5ΞΌs = 0.09kJ Pulse efficiency 0.95 Pulse forming system efficiency 0.98 Charger efficiency 0.96 Power efficiency 0.94 Overall Modulator efficiency 89% D. Nisbet & D. Aguglia Ph. Lebrun HF 2014 Beijing
25
Accelerator systems: RF βSmartβ RF loads
RF-to-DC power conversion F.Caspers, M. Betz, A. Grudiev & H. Sapotta, Design concepts for RF-DC conversion in particle accelerator systems, IPAC10 High-temperature heat recovery S. Federmann, M. Betz, F.Caspers, RF loads for energy recovery, IPAC12 Ph. Lebrun Workshop on Magnet Design Nov 2014
26
Workshop on Magnet Design Nov 2014
Infrastructure systems: cryogenics COP of cryogenic helium refrigerators (installed) Ph. Lebrun Workshop on Magnet Design Nov 2014
27
Cryogenic refrigeration Efficiency degrades at reduced capacity
Ph. Lebrun Workshop on Magnet Design Nov 2014
28
Workshop on Magnet Design Nov 2014
Infrastructure systems: cooling & ventilation Efficiency of heat transport in water vs. air Heat to be extracted π= π πΆ βπ Mechanical power on coolant π= π βπ π π with π = circulator efficiency Specific power π π= βπ π π πΆ βπ π=0.5 Ph. Lebrun Workshop on Magnet Design Nov 2014
29
Summary Reasons for low efficiency
For all types of machines, the average beam power is proportional to the product of particle energy and luminosity or delivered particle flux The energy-luminosity performance, and possibly the physics reach of a collider can be represented by a single βcoefficient of performanceβ The ratio of βcoefficient of performanceβ to beam power quantifies the relation between collider performance and beam parameters: it is lower for single-pass machines than for circular colliders βIntrinsicβ losses due to basic physics processes add up to the beam power and often exceed it (synchrotron radiation) Accelerator systems and infrastructure represent the bulk of electrical power consumption Comparing total power consumption and average beam power yields very low values for overall βgrid-to-beamβ efficiency Linear colliders show higher overall βgrid-to beamβ efficiencies than circular colliders. This partly compensates for their much lower COP/beam power ratio Ph. Lebrun Workshop on Magnet Design Nov 2014
30
Outlook Strategies for better efficiency
Maximize energy-luminosity performance per unit of beam power Minimize circumference for a given energy (high-field magnets) Operate at beam-beam limit Low-emittance, high-brilliance beams Low-beta insertions, small crossing angle (βcrabbingβ) Short bunches (beamstrahlung) Contain βintrinsicβ losses Synchrotron radiation Beam image currents Electron-cloud Optimize accelerator systems RF power generation and acceleration (deceleration) Low-dissipation magnets (low current density, pulsed, superconducting, permanent) Optimize infrastructure systems Efficient cryogenics (heat loads, refrigeration cycles & machinery, distribution) Limit electrical distribution losses (cables, transformers) Absorb heat loads preferably in water rather than air Recover and valorise waste heat Ph. Lebrun Workshop on Magnet Design Nov 2014
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.