Rail Production

TL;DR

  • Purpose: Aluminum guide rails for electromagnetic acceleration
  • Material: Cryogenic aluminum (cooled to -180°C)
  • Mass: ~70 t per Mass Driver* (hollow profile, 1 km track)
  • Wear: Replacement every 3-6 months (100-140 t/year per Mass Driver)

*Extended tracks: 2 km (~140 t), 3 km (~210 t).

Overview

Mass Driver rails are aluminum guides along which the projectile (container with mirror) travels. The rails serve simultaneously as: - Guides for the projectile - Electrical conductors - Part of the electromagnetic circuit

Rail Design

Parameter Value
Material 99.5% pure aluminum
Cross-section 200x300 mm (hollow profile, 15 mm wall)
Segment length 10 m
Segments per track 100* (for 1 km track)
Rail pair (2 pcs) ~70 t Al per Mass Driver*

*Extended tracks: 2 km (200 segments, ~140 t), 3 km (300 segments, ~210 t).

Rail Profile

        300 mm
   +--------------+
   | +----------+ | <- 15 mm wall
   | |          | |
   | |   NaK    | | 200 mm  (cooling cavity)
   | |          | |
   | +----------+ |
   +--------------+

Wall cross-section: 14,100 mm² (0.0141 m²)
For 2 rails x 1 km: 28.2 m³ Al -> ~76 t

Rail Manufacturing

Production Process

Stage Equipment Output
Billet casting with core CCM-Al with ceramic core 100x100 mm billets with 50 mm channel
Rolling to profile Rolling mill 200x300 mm profile with channel
Cutting to segments Plasma cutting 10 m segments
Heat treatment Induction furnace Stress relief
Surface polishing Grinding mill Ra <1 um

Note: The cooling channel is formed during casting using a ceramic core (MgO), which is then removed.

Details: Rolling Mill, Grinding

Cryogenic Cooling

Problem: Aluminum has 60% of copper’s conductivity at room temperature.

Solution: Cooling to -180°C increases aluminum conductivity by 6x.

Material Conductivity +20°C Conductivity -180°C
Copper 100% 400%
Aluminum 60% 360%

Conclusion: Cryogenic aluminum at -180°C has conductivity nearly equal to copper at room temperature.

Cooling System

Parameter Value
Coolant NaK (sodium-potassium alloy)
Coolant temperature -150°C
NaK flow rate 100 L/min per track
Radiators Directed into shadow (-180°C)
Pump power 100 kW

Rail Wear

Causes of Wear

Cause Contribution Consequences
Electrical arcing 40% Surface erosion
Mechanical abrasion 30% Groove formation
Thermal cycling 20% Microcracks
Oxidation 10% Darkening, corrosion

Aggravating factor: 1275g acceleration creates very high mechanical loads over a short time (0.4 sec).

Service Life

Operating Mode Launches Service Life
Intensive (600/day) ~50,000 3 months
Medium (300/day) ~50,000 6 months
Light (100/day) ~50,000 1.5 years

Material Balance

Per 1 Mass Driver (new, 1 km track):

Component Al Mass Production
Rails (2 pcs x 1 km) ~70 t 42 t/day -> 1.7 days

Replacement (wear, 1 Mass Driver/year):

Mode Replacements/year Al consumption/year
Intensive 4 280 t
Medium 2 140 t
Light 0.7 ~50 t

At 1000 Mass Drivers (intensive mode): 280,000 t Al/year for rail replacement alone.

Quality Control

Parameter Test Standard Action on Deviation
Conductivity 4-point resistance measurement >95% IACS Remelting
Flatness Touch probe +/-0.5 mm Grinding
Microcracks Visual (cameras) + load test No visible defects Rejection
Surface finish Visual (cameras) Ra <1 um Polishing

Rail Installation on Track

Stage Time Robots
Trench preparation 2 weeks 10 Moles-M
Frame installation 1 week 20 Centaurs-M
Rail mounting (100 segments) 1 week 20 Centaurs-M
Joint welding 3 days 10 Centaurs-M
Cooling connection 3 days 10 Centaurs-M
Calibration 1 day Automation

TOTAL: ~3-4 weeks from trench to ready rails. (Runs in parallel with frame and coil installation.)

See Also