Top level overview of target injection and tracking tasks

High Average Power Laser Program Workshop

Princeton Plasma Physics Laboratory

October 27 and 28, 2004

Presented by

Dan Goodin

at the

1. What is target injection and tracking?

2. What are the basic requirements?

3. What are the issues to be addressed?

4. What’s being done?

Summary - target injection, tracking, and beam steering

1. Build an injector that accelerates targets to a velocity to traverse the chamber (~6.5 m) in 16 milliseconds or less.

2. Demonstrate target tracking with sufficient accuracy for a power plant (+/- 20 microns).

Phase I injection/tracking/steering tasks

Phase I goals for target injection and tracking:

TurboPumps

Gun Barrel

TargetCatcher

Target Position

Detectors

Sabot Deflector

RevolverChamber

ExpansionTanks

73

R 7 mT ~1500 C

Injection, tracking, & steering requirements are “challenging”

• Inject about 500,000 targets per day (~6 Hz) for 1000 MW(e)• High velocity - ~400 m/s, separable sabot for handling/accelerating• Acceleration limited to about 1000 g’s (for “real” cryo target, TBC)• Need membrane support to avoid point-loading of target• Reliable, repetitive placement to 5 mm• Direct drive tracking and beam steering to 20 m• Integration of tracking & beam steering (reference system)

1) Showing a method to repetitively inject targets at high velocity- Gas gun demo- “Advanced” injection methods

(EM injector)

2) Showing in-flight tracking to 20 m- Ex-chamber tracking demo- Develop in-chamber tracking

methods

What are the issues and what’s being done?

We have demonstrated with the gas-gun:-Rep-rated operation (6 Hz, “burst” mode)-Two-piece sabot separation and deflection-Membrane support of target in sabot -Injection velocity of ≥400 m/s-Time “jitter” at chamber center of ~ 0.5 ms-In-flight tracking-Target placement accuracy at one sigma of 10 mm

Sabot separation at 400 m/s

Approximately 25 meter length reflects SOMBRERO plant fueling layout

Evaluating/testing electromagnetic, non-contacting coil gun design for the future

3) Showing how to integrate the tracking and beam steering systems- Conceptual designs and analyses

4) Showing target survival during the injection process- Modeling of DT heatup during injection- Modeling of DT response to heatup- Experiments with rapid DT heatup- Measurements of DT strength

What are the issues and what’s being done (continued)?

488nm guide laser

Poisson spotdetector

Target chamber

Reference “Sphere”Space frame15m

Reference sphere to define target chamber center

Simulation of 18K target entering 4000K chamber gas

Tmax = 4.36 103 KTave = 1.42 103 KVmax = 261.7 m/s

Axisymmetric

Chamber conditions affect heatup and tracking

DT cell for rapid heatup

testing

Design of cell for measuring

strength of DT (2mm X 2mm

view)

The presentations deal directly with these issues………

Talks in this session:

1) Target survival during injection - René Raffray

2) Target injection issue, background gas and plasma - David Harding

3) In-chamber tracking and integration with beam steering - Graham Flint

4) Status of target injection experiments - Dan Frey

5) Status of target tracking experiments - Ron Petzoldt

Injection experiment setup to simulate full-length of Sombrero fueling

In-flight tracking at 400 m/s