HIFVNL template

1
NDCX-II and Beyond Joe Kwan June 2, 2009AFRD
Division ReviewLawrence Berkeley National
Laboratory
2
NDCX-II Project Goals

• The primary goal is to build an accelerator for
  WMD experiments using 11M, and 30 months.
• Constraints
• Reusing the ATA induction cells for beam
  acceleration was in the original NDCX-II proposal
  
• Use existing building to save cost and
  construction time
• Approaches
• Design a flexible machine to allow both WMD and
  HIF/IFE target physics experiments as well as HIF
  driver studies
• Consider solenoids, electric quads and magnetic
  quads beam focusing choose the one that is most
  effective
• Different ion species for different target
  materials

3
NDCX-II is ideally suited for heating foils to
WDM regime
LITHIUM ION BEAM BUNCH Final Beam Energy gt 3
MeV Final Spot diameter 1 mm Final bunch
length 1 cm or 1 ns Total Charge Delivered
gt 20 nC
mm foil orfoam TARGET
Exiting beam available for dE/dx measurement
30 J/cm2 isochoric heating will raise aluminum
temperature to 1 eV
4
NDCX-II generates short pulses needed for
isochoric heating

• Key Concept
• Rapid longitudinal pulse compression.
• Strong focusing to confine a high charge-density
  beam.
• Neutralized final focusing to a small spot size
  on target.

gt 3 MV, 20 nC
Ion source 500ns
Target foil
accel-decelinjector provides pre-bunching
Induction Linacprovides custom waveforms for
rapid beam compression
Neutralized drift compression and final focus

• Key design parameters
• 100 mA Li Ion source at gt 1 mA/cm2.
• Induction cell voltage average gradient 0.25 MV/m
  (peak 0.75 MV/m).
• Build new 2T solenoids for beam transport.
• Use existing 8T solenoid for final focus.

5
Induction linacs are ideal for high-current
short-pulse beams

• An induction linac works like a series of
  transformers using the beam as a single-turn
  secondary.
• Volt-seconds in the core material limits the
  pulse length.
• Applied voltage waveforms determine the
  acceleration schedule.

Advanced Test Accelerator (ATA)
DARHT-II
DARHT-II
6
Schematic of the ATA Induction Cell
HV FEED
INSULATOR
OIL
VACUUM
1.5 3 T PULSED SOLENOID
BEAM
5.5
FERRITE TORROID(70 ns, 250 kV)
11.0
7
A simple passive circuit can generate a wide
variety of waveforms
ATA compensation box
charged line
induction cell accelerating gap impedance

• Waveforms needed for NDCX-II

8
NDCX-II will reuse gt30 ATA induction cells (a
30M value)
100mA, 500ns Li ion injector
water-filled Blumleins
oil-filled transmission lines
30 ATA induction cells with pulsed 1-3T
solenoids Length 15 m
final energy correction induction cell
neutralized drift compression region with plasma
sources
final focus and target chamber
9
NDCX-II will coexist with NDCX-I in LBNLs
Building 58 high bay
10
NDCX-II ion source and target are similar to
NDCX-I
Injector

• Text goes here

Targetchamber
102 kV pulsed source
68 kV DCextraction electrode
-170 kV DCaccel electrode
NDCX-I NDCX-II Ion mass K (A39) Li (A7) Ion
energy 350 keV gt 3 MeV Focal spot diameter 2
mm 1 mm Pulse duration 2 4 ns 1 ns Peak current
2 A 30 A
11
The NDCX-II baseline physics design effectively
combines acceleration and compression

• Run 1-D Particle-in-cell (PIC) code with a few
  hundred particles for design synthesis
• Models gaps as extended fringing field.
• Self-field model guided by results from Warp
  runs.
• Can use realistic acceleration waveforms.
• Also include centroid tracking for study of
  misalignment effects.
• Run comprehensive PIC code Warp for detailed
  design
• 3-D and axisymmetric (r,z) models.
• Electrostatic space charge and accelerating gap
  fields included.
• Time-dependent space-charge-limited emission.
• Extensively benchmarked against experiments and
  analytic cases.
• A. Friedman, R. Cohen, D. Grote, E. Henestroza,
  S. Lund, W. Sharp, W. Waldron.

12
NDCX-II beam experiments are relevant to HIF
drivers

• HIF driver-like compression of non-neutral and
  neutralized beams.
• Explore limits on velocity tilt.
• Employs space charge to remove velocity tilt.
• Longitudinal beam control.
• Chromatic aberration in final focus.
• Possible to add a quadrupole transport section at
  the end.
• Beam diagnostic development.

Beam Compression in NDCX-II
Pulse length (m)
Center of mass z position
13
Use the Warp code to simulate the NDCX-II beam in
(r,z)
14
Warp-3D to Simulation for NDCX-II
15
NDCX-II Electrical Systems

• Injector high voltage pulsers (2) and power
  supply (1) for beam extraction
• Pulsed power systems (34) to produce the
  acceleration and compression waveforms at the
  induction cells
• 10 spark gap switched lumped element or
  transmission line pulsers
• 24 ATA Blumleins with shaping elements at cells
• High current pulsers (40) for the transport
  solenoids in the induction cells and intercells
• Correction dipole pulsers (2 per solenoid)
• Plasma source pulsers
• Control system 200 power supplies
• Timing and trigger system 200 triggers
• Data acquisition system 300 diagnostics
• Interlock system 100 status monitors

16
The NDCX-II Test Stand is operational and testing
the performance of various hardware components
Charging transformer
Spark Gap
Blumlein
Oil-filled transmission line
Thyratron switch chassis
Shaping network
Charging supplies and trigger generators
Cell
17
Key technical areas are under risk management

• Ion sourceLi current density of 1-2 mA/cm2 is
  achievable and has a matched beam solution.
  Development work has started. He is a possible
  option that requires less kinetic energy but
  higher current.
• Custom voltage waveforms for ion
  accelerationsensitivity study and test data are
  underway.
• Solenoid magnet alignmentuse state of the art
  mechanical alignment technique, and provide beam
  steering correction using dipole coils.
• Effect of pulsed solenoid and correction dipole
  field on the ferrite coresprototype testing is
  underway on an existing test stand. If proven
  necessary, we can use additional layer(s) of
  coils to trap the return field(s).
• Transient noise affecting beam diagnosticswill
  require careful shielding of stray fields.
• Beam neutralizationa plasma density much higher
  than NDCX-I can be produced.

18
Project schedule, milestones and reviews

• Major milestones dates
• May 1, 2009Official project start
• Mar 31, 2010Prototype induction cell completed
• Sep 30, 2010Refurbish induction cell 1-10
• Mar 31, 2011Accelerator block 1 installed
• Sep 30, 2011Project completion
• Project Reviews
• Advisory discussion meeting on May 27, 2009
• Lehman review in August 20-21, 2009
• Quarterly reviews by a Project Advisory Committee

19
NDCX-II Project Organization
AFRD Fusion Office
Project Manager Joe Kwan Project Engineering
Controls Matthaeus Leitner
Electrical EngineeringWill Waldron
Mechanical EngineeringMatthaeus Leitner
Facility Alignment Matthaeus Leitner
Controls Data Acquisition W. Waldron (acting)
Integration, QC Safety M. Leitner (acting)
Beam Acceleration Alex Friedman
Beam Neutralization Erik Gilson
Ion Source Injector Joe Kwan
Target Beam Diagnostics Frank Bieniosek
20
Experiments Planned for NDCX-II
Constant dE/dx near Bragg peak

• Examine basic physics of warm density matter
  regime (kT 1 eV), e.g., EOS, conductivity,
  liquid-vapor metal phase transition.
• Positive-negative halogen ion plasma (kT 0.4
  eV).
• Ion-beam-driven IFE-relevant target physics,
  e.g., ion coupling efficiency to an ablating
  plasma, and the hydro-dynamics.
• Study space-charge-dominated ion beam dynamics
  and the effects of secondary electrons.
• Study collective beam-plasma interaction
  processes, beam focusing, and compression in a
  neutralizing background plasma.

temperature (eV)
density (g/cm2)
Figure from R. Lee
21
The time is right to restart a serious design
effort toward heavy ion inertial fusion energy.
The Integrated Research Experiment (IRE) concept
(2002) integrate beam dynamics, driver
technology with HIF specific indirect drive
target physics experiments.
2002, Snowmass
A new direct drive target design with Edriver
0.5 MJ, has gain 50. Eion 0.5 GeV, so it
might be explored on an IRE scale accelerator.
Logan, Perkins, Barnard, Phys. Plasmas 15 (2009)
072701.
22
LBNL should maintain a preeminent role in energy
research, including inertial fusion
fusion/fission hybrids

• We are developing expertise in ion beam heating
  for HEDP WDM. Energy research is a natural
  complement.
• NDCX-2 will be a test bed for fusion relevant
  longitudinal dynamics experiments (acceleration
  and compression), but it is primarily designed to
  address warm dense matter physics (not IFE).
• LDRD proposal to broadly assess the potential of
  ion-driven fusion-fission hybrid, spallation.
• LIFE proposal to leverage NIF for inertial fusion
  energy development and burning of fission waste.
• S. Chu looking at hybrid solutions of fusion
  fission creates high-energy neutrons that can
  burn down the long-lived actinides. Technology
  Review (2009)http//www.technologyreview.com/busi
  ness/22651/page1/
• We propose a serious and timely effort. It
  requires more than nominal support!

23
Conclusions

• NDCX-II will be a unique ion-driven user facility
  for warm dense matter and IFE target physics
  studies.
• The machine will also allow beam dynamic
  experiments to study high-current drivers.
• The baseline physics design makes optimal use of
  the ATA accelerator components through rapid beam
  compression and acceleration.
• The project is expected to start in May 2009, and
  complete construction by September 2011.
• NDCX-II is a prerequisite for the Integrated
  BeamHigh Energy Density Physics Experiment in
  the 2007 DOE Office of Science Strategic Plan.
• With NIF starting operation, now is the time to
  ramp up effort toward inertial fusion
  fusion/fission hybrids.

24

• Backup Slides

25
Evolution of the phase space and the line charge
density
peak compression
entering linac
mid-compression
Ek (MeV)
? (?C/m)
z (m)
expanding
exiting
at focus
26
NDCX-II will modify and change configuration of
ATA hardware

• Pulsed 3T solenoid instead of 5kG DC solenoid
• Effect of the solenoid return flux on the
  available core volt-seconds is being studied on
  the test stand
• Mismatched load for Blumlein to generate
  compression waveforms
• Derating the Blumlein output voltage from 250kV
  to 200kV
• Higher safety margin on insulators to protect
  from possible high amplitude reflections which
  are a result of impedance mismatching
• Offsets the potential partial saturation of
  ferrite from solenoid return flux
• DC charging of the switch chassis instead of the
  CRC system
• Simpler and adequate for the much lower
  repetition rate

27
NDCX-II will modify and change configuration of
ATA hardware

• Separate trigger system for each Blumlein instead
  of distributed Blumlein pulse for triggering many
  Blumleins
• Beam transit time is too long for cable delays
• System jitter using a commercial 100kV trigger
  generator is being studied on the test stand
• One transmission line between Blumlein and cell
• Obvious mismatch, but load is not matched either
• Step-up for nominal flat pulse
• Simpler installation
• Feed cell from alternating sides to cancel minor
  dipole effect
• X and Y corrector for each solenoid
• Effect of the saturating ferrite during the reset
  and main pulse on dipole strength is being
  studied on the test stand

28
NDCX-II Cost and Labor Profiles
First Procurements Charged
M 5.8 MS, M 5.2 Labor
Average 10 FTE on NDCX-II project funds

• Estimate assumes a cost contingency of 20 for
  the project