EC Systems Status & Prospects - Nucleus Meeting Proceedings/4th DEMO... · “pen point” a spot...

EC Systems Status & Prospects

4th IAEA DEMO

Programme Workshop

15–18 November 2016

Karlsruhe, Germany

Presented by G.G. Denisov

Institute of Applied Physics, Nizhny Novgorod, 603950, Russia

Gycom Ltd, Nizhny Novgorod, 603155 Russia

2

• M.Henderson. ITER IO

• EU team (S. Garavaglia, W. Bin, A. Bruschi, G. Granucci,

G.Grossetti, J.Jelonnek, A. Moro N. Rispoli D. Strauss,

M.Thumm, Q.M. Tran and T. Franke, …)

• R. Ikeda. QST, Naka, Japan

• T. Kariya. University of Tsukuba, Japan

Russian colleagues from

• Institute of Applied Physics

• Gycom Ltd,

• Kurchatov Institute

• ITER DA

• RT Soft

Contributions:

3

OUTLINE

• First steps and main events

• List of running and near future EC systems

• EC systems: aims and content

• ITER EC system

• Necessary steps from ITER to DEMO

• New developments for future EC systems

o Higher gyrotron frequency

o Multi-frequency operation

o Broad band window

o Remote steering launcher

Summary

4


• List of running and near future EC

systems


• ITER EC system


• New developments for future EC

systems



o Broad band window


Some dates from “ancient” history

1964 – first experiments with gyrotrons

70s – 100 GHz/1MW/ 100 mks/ TE22.2

28 GHz/100kW/CW

first use to heat plasma at TM-3, TUMAN-2

80s – 100GHz/2.1MW/10mks/coax./

0.5 MW/sec

wide use in plasma experiments

Main Events

1990-2006

First depressed collectors in megawatt gyrotrons

First CVD diamond gyrotron windows

Demonstration of CW operation of MW power gyrotrons

Remote steering antenna concept

MW gyrotron complexes at major fusion installations

Last decade 2007-2016

Great progress in ITER system development

• Demonstrated required gyrotron parameters/Reliability tests

• Manufacturing began

Results on 1.5-2 MW gyrotron models

Multi-frequency gyrotrons

Higher frequency gyrotrons (first steps)

New ideas

ECW systems (examples)

Future installations:

ITER 24 1MW/170GHz/3600 sec 2025

JT-60SA 7 110/138 GHz/100 sec 2019

DEMO 50 MW/ 230 GHz/ CW

Running installations with ECW systems:

DIII-D, FTU, TCV, JT-60U, LHD, ASDEX-Upgrade, T-10, W7-AS, …

80-170 GHz/ 2-5 MW/1-10 sec

Developments for running machines:

EAST 140 GHz/ 5 MW/ 1000 sec

KSTAR 105/140 GHz/ * MW/ 300 sec

W7-X 10 1MW/140GHz/ 1800 sec

JET just discussions since 2000

8




• ITER EC system


• New developments for future EC systems o Higher gyrotron frequency


o Broad band window


How ECH works

9

Beam steering from external system

(mirrors in upper port)

mm-wave beams launched from

either the upper or equatorial ports

Power absorbed locally,

where B satisfies:

Microwaves give energy to electrons when

electron cyclotron resonance occurs

10

Heating and Current drive source

that is both localized and steerable

Barrier(window) is possible

Localized: 4cm to 20cm deposition width

Useful for:

ECH is a surgical tool that can

“pen point” a spot in the plasma cross section

to heat plasma and/or drive current

Current Profile Tailoring

deposit ˜0.8MA from center to mid radius

edge center

EL

MHD Control

deposit ˜0.2MA inside rotating 4cm island

UL

EC system includes

Main components

• Gyrotrons (many)

• Transmission lines (many) HE11 waveguide or mirrors

• Barrier windows (many)

• Launchers (several)

Aix components

• HV and LV power supplies

• Control system

• Cooling system

• Safety

Ramp-down Helps to ramp-down plasma softly

Tailors current profile to avoid instabilities

EC is used through out the Plasma Discharge

12

EC Power

Plasma Current

Start-up “Provides “spark” to initiate plasma

Ramp-up Good absorption when plasma is not “hot”

Helps to build up temperature and current

Tailors current profile for stabilising plasma

Helps to achieve High confinement mode

Burn Tailors Current profile

Controls sawtooth and NTMs

maintains “hot” plasma

Ramp

down Startup Ramp

up Burn

Based on existing practices (AUG, DIII-D, JT-60U, TCV, etc)

TID: Targeted and Impacts Design // TND Targeted and Not impacting Design

EC “App” Matrix

ITER EC Targeted Physics Functions

13

14




• ITER EC system




o Broad band window


ITER Electron Cyclotron System

15

Method Advantage Disadvantage

EC Couples high power

microwaves to e

Extremely localized heating

and current deposition

Uses external actuators to

change deposition location

Effectively 100% coupling

- Indirect heating of ions

- Limited long pulse high

power experience

Power Supplies (50MW)

24 sources (24MW)

24 Transmission

lines

5 Launchers (20MW)

NTM control

16

Upper Launcher optics designed for:

Deposition 4 to 8cm

Power can modulate up to 5kHz

24 beams overlap in plasma (very narrow profiles)

Upper Launcher is like a ‘predator drone’:

it watches plasma from above and hits each island as they rotate in sight

Last mirror steers deposition over 50% of plasma

Equatorial Launcher

17

Primary Role

Note that beams now steer in poloidal direction

Nuclear

Occupational

Safety

EC Functional Requirements

18

Compliance with Load Specifications

Nuclear

Seismic

Plasma

Vacuum

Over pressure events

Seismic

Environmental

Fire

Combined loads

Integration

RAMI (reliability, availability, maintainability, inspectability)

EC HCD Applications (Baseline and Power Upgrades)

First Plasma Operations (inject 6.7MW)

Second Plasma Operations (inject 20MW)

Upgrade Operations (inject additional ≤20MW)

EU IN JA RF US

PS 8 sets 4 main 8 APS/BPS

RF Source 6MW 2MW 8MW 8MW

TL 24

Launchers 4 (UL) 1 (EL)

DAs have chosen the EC System Procurements Divisions

19

5 Parties provide in-kind procurement

of the 4 EC subsystems

Requirement: >39%

Achieving: between 39 and 44%

(does not include services)

Electrical Efficient from Grid to Plasma

Plug to Plasma Efficiency

20

Actuators: Launchers

21

Upper launcher 4 ports, 8 entries each

Control of MHD activity (NTMs)

Equatorial launcher: 1 Port, 24 entries

Central heating and current drive

20MW

Switch

(≤3 sec)

EC Transmission Line

22

Microwave Sources

Tokamak

Transmission Line Path

Length ˜160m

Power Handling 1.4MW

Pulse length 3’600s (25% duty cycle)

Power Transmission Efficiency ≥90%

Mode conversion efficiency ≥95%

Transmission Line Overview:

Universal Polarizer (>99% O or X mode coupling)

Actuators: Transmission Line

23

24 switches directing power to either EL or UL

8 switches directing power to UL “upper” or “lower” Steering mirrors

Switching speed ≤3 sec

Polarization change ≤2 sec

EC system has to comply with Tritium Confinement

Safety

24

Diamond window

All-metal valve

Shutter Valve

Cathode (~-60kV)

@~1’000 C

Body (~+30kV)

Collector (ground)

electron beam

SC magnet

RF power

(~1MW)

Resonator

mm-waves

mode convertor

JA RF EU IN

TBD

1MW

1000s

50-55%

1MW

1000s

53%

0.8MW

100s

pulse length of 3’600sec

1MW at window with ≥95% TEM00 mode purity

LHe free cryomagnets

>50% efficiency (Pout/Pin)

170GHz Gyrotrons are rated for:

RF Sources (Gyrotrons)

25

Challenges:

Mass production

High Reliability

Higher Power (≥1.0MW)

Long life (≥5 years)

High mode purity (≥98%)

Partial Power modulation

5kHz

0.1mT < |Br| < 0.25mT (or

less)

HVPS: Main and Body for EU and RF gyrotrons

26

Main High Voltage Power Supply

(PSM based)

Parameter Value

Voltage ∼55kV

Current ∼110A

Pulse Length 3’600 sec

Duty cycle 25%

Body Power Supply

(PSM based)

Parameter Value

Voltage ∼35kV

Current <100mA

Pulse Length 3’600 sec

Duty cycle 25%

EU contract signed with

Ampegon

Current increased for

1.2 to 1.4 MW Gyrotrons

2025: first plasma (1 UL, 8MW EC for plasma initiation and maybe EL)

2028: second plasma and full 24MW EC system

<2035: D-T phase

General ITER EC Planning

Schedule: Objective at System Level

27

EC manufacturing, assembly and Operation Schedule

2018: Access to RF Building

2018-9: Start installation of PS, Gyrotrons, TL

2023-24: 1 UL plug and 8MW ready for operation

2024: All ex-vessel installed, ≥1 year commissioning for First Plasma

2027: All launchers installed

2028: Full system operating

2031: (Full NB and IC operating)

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Current activities. Russian team. IAP/GYCOM

Gyrotrons/TL components for plasma fusion (2015-2016)

• ITER activity

• EAST (first ECW experiment) +1

• KSTAR (first delivery in 2015, acceptance test

completed) +1

• Asdex Upgrade

• TCV

• EU DA….

• New developments

ITER RF Source prototype

False floor

removed

Ion Pump Power Supply

Collector Sweep coil

Power Supply

Cathode Filament

Power Supply

Super Conductive

Magnet Power Supply

Gun Coil Power Supply

Collector DC coil Power

Supply

X and Y Correction coils Power

Supplies

Temperature Monitor

PROTOTYPE OF RF-DA RF POWER SOURCE, TEST REPORT

May 11 – 15, 2015, Nizhny Novgorod, Russia

Gyrotron together with

SCM, MOU and relief load

in the support structure

left picture

Waveguide with terminal

load and cooling manifolds

top right

Operator console with

control &protection cubicles

bottom right

Russian ITER RF Source pre-prototype

0

100

200

300

400

500

600

700

800

900

1000

1100

1 51 101 151 201 251

pulse sequencial number

pu

lse

du

rati

on

, s

regular cut-off internal arc

Gyrotron run test (2014) at 1MW output power

with pulse duration 500s and 1000s

Reliability > 95%

500s – 160 pulses

1000s – 55 pulses

New tube

conditioning

PROTOTYPE OF RF-DA RF POWER SOURCE TEST REPORT (Section 5)

May 11 – 15, 2015, Nizhny Novgorod, Russia

5. PRFS main output parameters

measurement and verification for

compliance for specified ones:

- operation frequency,

- power at the MOU output,

- generation efficiency

- НЕ11 mode content at MOU output

- pulse length

- duty factor

Required

170±0.25 GHz

≥0.96 MW

≥50%

≥95%

≥1000s

≤1/4

Measured

170.07 GHz

0.96 MW (±5%)

58%

97±1%

1000s

1/4

PRFS testing was carried out on Factory site following RF source prototype FAT Program

IDM_NCNC85 v.1.0 in presence of ITER organization (IO) representatives: C. Darbos, F. Gandini

and P. Vertongen.

FDR, October 2015; Manufacturing began in 2016

Two-frequency 140 / 105 GHz gyrotron with 1 MW output power and maximum pulse

duration 300 s. The parameters were successfully demonstrated at the customer site – NFRI /

Korea. At present time gyrotron operates at plasma machine KSTAR. Second two-frequency

gyrotron is planned for delivery to NFRI at the end of 2017.

140 GHz / 1 MW / 1000 s gyrotron operates at EAST machine / ASIPP / China since

mid of 2015 year. Second tube passed factory tests at July, 2016 and delivered to China.

The deliveries besides the gyrotrons include other components: cryomagnets

(JASTEC, Japan), matching optic units, elements of evacuated transmission lines and full

power evacuated dummy load.

Gyrotrons at factory and customer sites

Other gyrotrons for fusion installations (2/6)

34




• ITER EC system




o Broad band window


35

Necessary steps from ITER to DEMO

• Frequency increase 170 −−−> 230 GHz

• Module power increase 1.0 −−−> 1.5 MW

• Eff./reliability enhancement 50 −−−> 60 % / 95 --> 98%

• Multi-frequency operation avoid wide angle scanning

• Remote steering remove mirrors from magnetic field

and plasma

Mutual contradictions in goals

e.g.

- Higher frequency and higher power require bigger gyrotron cavity,

higher operating mode (affect gyrotron efficiency)

- More critical transmission line alignment (for higher f and P)

36




• ITER EC system


• New developments for future EC systems



o Broad band window


37

New developments, Russian team

• higher power and higher frequency gyrotrons

• phase locking of gyro-oscillator by external signal

Aim:

• Provide single mode gyrotron operation at very high-order modes

• Stabilize frequency while e-beam parameters are not stable

• Enhance efficiency

• Lock frequency and phase / Make several gyrotrons coherent

T. Kariya, T. Imai, R. Minami, T. Numakura, K. Tsumura, Y. Ebashi, Y. Endo, R. Ikezoe, Y. Nakashima : Plasma Research Center (PRC), University of Tsukuba

K. Sakamoto, Y. Oda, R. Ikeda, K. Takahashi, T. Kobayashi, S. Moriyama : National Institutes for Quantum and Radiological Science and Technology (QST)

T. Shimozuma, S. Kubo, Y. Yoshimura, H. Takahashi, H. Igami, S. Ito, K. Okada, S. Kobayashi, T. Mutoh : National Institute for Fusion Science (NIFS)

H. Idei, K. Hanada : Research Institute for Applied Mechanics, Kyushu University

K. Nagasaki : Institute of Advanced Energy, Kyoto University

M. Ono : Princeton University Plasma Physics Laboratory (PPPL)

T. Eguchi, Y. Mitunaka : Toshiba Electron Tubes and Devices Co., Ltd (TETD)

Univ. of Tsukuba is developing over 1 MW gyrotrons of

14GHz to sub-THz for Fusion Devices and for Demo-Reactor

in collaboration with

QST, NIFS, Kyushu Univ., Kyoto Univ., PPPL and TETD, based on 2 MW level result on the LHD 77 GHz gyrotron tube

FIP1-6Rcz

Development of Over MW Gyrotrons for Fusion at Frequencies from 14 GHz to Sub-terahertz

Presented by T. Kariya (Univ. Tsukuba)

Develop. of Sub-Terahertz (300 GHz) Gyrotron For ECH and ECCD at the DEMO reactor (Collabo. with QST)

Achieved 299.8 GHz, 522 kW, 2 ms with TE32,18 single-mode

Output Window Reflectance : 0% for TE32,18, 23% for TE30,19

With SiO2 disk 20% for TE32,18,2% for TE30,19

Window reflection affects the oscillation mode characteristics, which can be removed by installing a built-in mode converter. The aimed design single mode would be realized. M

ain

Co

il C

urr

en

t [A

]

Mai

n C

oil

Cu

rre

nt

[A] Gun Coil Current [A] Gun Coil Current [A]

Mode maps (cavity vs. gun coil current) 295.65 GHz, 542 kW (TE31,18) 301.8 GHz, 528 kW (TE30,19)

220 - 240 GHz Oscillation by 300 GHz GyrotronMagnetic Field

at Cavity [T]

Beam Radius

[mm]

Estimated

Oscillation Mode

Estimated

Frequency [GHz]

10.11 5.57 TE28,15(-) 253.99

9.80 5.58 TE27,15(-) 250.04

9.60 5.59 TE28,14(-) 243.9

9.54 5.59 TE25,15(+) 242.1

9.43 5.6 ? ?

9.07 5.61 TE24,14(+) 228.13

8.90 5.62 TE26,13(-) 225.96

It was found that designed ultra-high volume mode of sub-THz would be stably obtained with conventional cylindrical cavity. Step tunable single mode oscillations were also confirmed. These result contributes greatly to the step frequency tunable gyrotron in the sub-THz region for the DEMO-Reactor.

300kW

Stable single mode oscillation at each tuned freq. in 225–254 GHz band

Develop. of Sub-Terahertz (300 GHz) Gyrotron For ECH and ECCD at the DEMO reactor (Collabo. with QST)

short pulse, efficiency

Design study of 154/116 GHz Dual-frequency gyrotron -----

For ECH and EBW heating at LHD (Collab. With NIFS)

Three 77 GHz and two 154 GHz gyrotrons have contributed greatly to extending the LHD plasma performance with their total plasma injection power of 5.4 MW. • High Te plasma : Te = 20 keV • Steady-state plasma : line averaged ne = 1.1× 1019 m-3 Te = 2.5 keV was sustained for 2351 s.

Based on the above and the 2 MW level 77 GHz gyrotron development results, a new 154/116 GHz dual-frequency gyrotron is desired for expanding the LHD plasma parameters.

Best matching of cavity, Mode convertor and window was obtained with combination of Cavity oscillation modes

TE28,9 at 154 GHz and TE21,7 at 116 GHz.

Oscillations with the power exceeding 1.5 MW are expected at 154 and 116 GHz.

The simulation of the MIG indicates the operation at α = 1–1.2 with Δα/α < 5 %, implying high efficient oscillations in the cavity.

1.5MW 1.5MW

DEMO EC System Conceptual Design by EUROfusion

EC Task Power (MW) Localization (ρ) Mode

Assisted Break-down 6-10 < 0.3 Heating

Ramp up and L-H transition 50 < 0.3 Heating/CD

Main Heating 50 < 0.3 Heating/CD

Sawtooth Control 2 0.3 CD

NTM control (2,1) and (3,2) 10-15 0.85; 0.75 CD

Ramp down 40 0.3 - 0.5 Heating

Main DEMO EC tasks with corresponding power required and deposition location, assuming the design value of 50 MW. For all these functions, a 100 % reliability is expected.

The Conceptual Design of the EC System bases on:

Physical requirements

Considerations for RAMI

100 % reliability

maximum availability

50

40

10

EC [MW]*

Ramp-down

BKD

Flat top

~10s ~200-300s

~2h ~200-300s

Ip

Main Heating/CD if requested

Ramp-up & L-H

transition

+ NTM stabilization

Sketch of DEMO1 Pulse * EC power required - w/o NBI, IC

G. Granucci et al., “Conceptual Design of the DEMO EC-System: Main Developments and R&D Achievements”, 26th IAEA FEC, Kyoto, 2016

EC System Architecture and Concept Studies

The EC DEMO system architecture is organized in identical CLUSTERs (6), allowing

modularity, reducing requirement for special components.

In each CLUSTER there is one gyrotron in stand-by to enter in case of fault.

HVPS Gy1

Gy2

Gy3

Gy4

Gy5

Gy6

Gy7

Gy8

RSA lower row

RSA upper row

Number of clusters: 4 + 1 for Equatorial Port + 1 for Upper Port To guaranty 100 % of reliability for 50 MW at any time of DEMO pulse

Each CLUSTER is composed by: 8 gyrotrons /2 MW total power 16 MW 14 MW injected 1 multi-beam EQO TL 1 HVPS with 8 outputs + 8 anode PSs +8 series switches 1 plug-in launcher with 8 launching points


Conceptual Studies on Transmission Line + Antenna

Main requirements for transmission lines:

- Efficiency target: 90 %

- Power handling capability: 2MW cw

- Multi-frequency (or broadband)

- Tritium compatibility

Proposal of Evacuated Quasi-Optical Multiple beam TL

Multi-Beam QO TL enclosed in a vacuum vessel

Reference design: mirror confocal layout

Vacuum duct: straight tubes with constant diameter

Mirrors (1 curved + 1 Plane) forming doglegs for TL bend

Pumping system at each unit length

L=distance between 2 focusing mirrors

Main requirements for antennas:

• Different tasks to be addressed (Heating, Off-axis CD…)

• No movable parts in the proximity of plasma

• Several Identical plug-in launchers

RSA feasibility study aims for:

• Wide steering for deposition control

• Optimal range for CD efficiency maximization

• Multi-frequency operation


Targets for EC Gyrotron R&D

• Operate at heating and at optimum current drive frequency

Frequency for current drive: >200 GHz (up to 240 GHz)

• Keep the number of gyrotrons as low as possible

Output power: >1 MW (target: 2 MW @ >200 GHz)

• Keep a high energy gain for the power plant

Total efficiency for a gyrotron >60 %

• Allow multi-purpose operation at optimum heating and current drive

frequencies (including a possible compatibility to ITER frequency)

Multi-purpose at n·l/2 of window resonances

Leaps of about ~34 GHz (e. g. at 136/170/204/238 GHz)

• Allow fast frequency step-tunability (2-3 GHz, ±10 GHz total bandwidth)

Broadband window technologies

Gyrotron Concepts under Consideration to Achieve the Target of 2 MW Output Power at >200 GHz

Conventional hollow-cavity design + simpler construction - more dense mode spectrum lower possible operating mode less output power

Coaxial-cavity design + Less dense spectrum of competing modes operation at very high-order mode higher output power + Reduced voltage depression - Risk of misalignment and too high thermal loading of inner conductor

TE43,15-mode TE49,29-mode

Towards >60 % Efficiency: Fundamental Studies on Possible Multi-Stage Collector Concepts

Two concepts under consideration:

Non-adiabatic concept

using axial symmetric

E- and B-field components

ExB drift concept

using non-axial symmetric field

components as proposed by

I. Pagonakis, 2008

Example for a collector using advanced ExB drift concept:

E- and B-field profiles

Electron trajectories

A gyrotron interaction efficiency of

35 % requires a concept for a depressed

collector which consists

of minimum 2-stages (𝜂𝑐𝑜𝑙 > 74 %).

Targets:

- Fast frequency step-tunability (2-3 GHz, ±10 GHz total bandwidth)

- Waveguide diameter >50 mm (min. 63.5 mm)

Towards CVD-Diamond Disc Brewster Angle Windows for Frequency Step-Tunable Gyrotrons

Innovative production

technologies for large-size

(>140 mm) CVD diamond discs

Advanced cooling technologies

New joining technologies

54

Summary • DEMO requirements much more stronger than ITER

• But great progress in gyrotrons in last 20 years

1 MJ (0.5MW/1 sec) 1 GJ (1MW/1000 sec), eff. 30 55%

this brings some optimism

• Lack of long pulse operation experience with TL and

launchers

the experience will come soon

• Aims of the new developments are:

• Reliability of the system operation

• Higher power and higher frequency

• Multi-frequency operation

• Remote steering antenna

Thank you!

EC Systems Status & Prospects - Nucleus Meeting Proceedings/4th DEMO... · “pen point” a spot...

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